SUPERCAPACITORS COMPRISING PHOSPHONATE AND ARSONATE METAL ORGANIC FRAMEWORKS (MOFS) AS ACTIVE ELECTRODE MATERIALS

Abstract

An electrode suitable for constructing an electrochemical double layer capacitor and/or supercapacitor is provided that includes an electrode material a metal organic framework (MOF), wherein the MOF includes an inorganic building unit including metal atoms selected from group 1 to group 12 elements, and functional groups of organic linkers including oxygen (O) and one or more atoms selected from the group comprising phosphorus (P), arsenic (As), antimony (Sb), silicon (Si), selenium (Se) and bismuth (Bi). The functional groups of the organic linkers can include phosphonate, arsonate, phosphonic acid, phosphinic acid, arsonic acids and/or arsinic acids, monoester and/or diester forms thereof. Further, the metal atoms may be selected from zinc (Zn), cadmium (Cd), copper (Cu), cobalt (Co), nickel (Ni), gold (Au) and silver (Ag). The use of the MOF as a semiconductor in semiconductor applications, a semiconductive device, such as a photovoltaic cell, including the MOF are also provided.

Claims

1. An electrode suitable for constructing an electrochemical double layer capacitor and/or supercapacitor comprising as an electrode material a metal organic framework (MOF), wherein the MOF comprises an inorganic building unit comprising metal atoms selected from group 1 to group 12 elements, and functional groups of organic linkers comprising oxygen (O) and one or more atoms selected from the group consisting of: phosphorus (P), arsenic (As), antimony (Sb), silicon (Si), selenium (Se) and bismuth (Bi).

2. The electrode according to claim 1, wherein the metal atoms are selected form the group consisting of: zinc (Zn), cadmium (Cd), copper (Cu), cobalt (Co), nickel (Ni), gold (Au) and silver (Ag).

3. The electrode according to claim 1, wherein the functional groups of the organic linkers are selected from the group consisting of: phosphonate, arsonate, phosphonic acid, phosphinic acid, arsonic acids and/or arsinic acids, monoester and/or diester forms thereof.

4. The electrode according to claim 1, wherein the MOFs comprise auxiliary linkers.

5. The electrode according to claim 1, wherein the functional groups of the organic linkers comprise arsonate and are synthetized using p-dimethylarsenato-phenylboronic acid.

6. The electrode according to claim 1, wherein the metal atoms and the functional groups of the organic linkers are bound to each other through covalent bonding, coordinate covalent bonding and/or an ionic bonding.

7. The electrode according to claim 1, wherein the MOF is porous.

8. The electrode according to claim 1, wherein metal atoms comprise Cu, Ni, Fe, Cd, Zn, Zr, Ti, V, Cr and/or Co and the functional groups comprise phosphonate and/or arsonate.

9. The electrode according to claim 1, wherein the MOF is [{Cu.sub.2(4,4′-bpy).sub.0.5}(1,4-naphthalenediphosphonate (NDPA))], [Co.sub.2(H.sub.4-MTPPA)].3NMP.H.sub.2O, [{Cu(H.sub.2O)}(2,6-NDPA).sub.0.5], [Zn{N(CH.sub.3).sub.2}(6-bromonapthalene-2-yl)phosphonate], Zn.sub.2H.sub.4MTPPA, Zn.sub.2H.sub.4STPPA, [Ni(Cu—H.sub.4TPPA)].2(CH.sub.3)2NH.sup.2+, Zn.sub.2(H.sub.4TPPA), Zn.sub.2(Cu—H.sub.4TPPA), Cu.sub.3(H.sub.5-MTPPA).sub.2, K.sub.6(m-H.sub.2-TPPA).2H.sub.2O, or [{Ca.sub.2(DMF)}(2,6-NDPA)].

10. The electrode according to claim 1, wherein [Co.sub.2(H.sub.4-MTPPA)].3NMP.H.sub.2O was prepared solvothermically from the tetrahedral linker tetraphenylmethane tetrakis-4-phosphonic acid (H8-MTPPA) and CoSO.sub.47H.sub.2O in N-methyl-2-pyrrolidone (NMP).

11. An electrochemical double layer capacitor or a supercapacitor comprising an electrode according to claim 1.

12. (canceled)

13. (canceled)

14. A semiconductor device or photovoltaic device comprising a metal organic framework (MOF), wherein the MOF comprises an inorganic building unit comprising metal atoms selected from group 1 to group 12 elements, and functional groups of organic linkers comprising oxygen (O) and one or more atoms selected from the group comprising consisting of: phosphorus (P), arsenic (As), antimony (Sb), silicon (Si), selenium (Se) and bismuth (Bi).

15. The photovoltaic device according to claim 14, wherein the photovoltaic device is a photovoltaic cell comprising the MOF as a photoactive material.

16. The electrode according to claim 2, wherein the metal atoms are at least one of Co, Cu and Ni.

17. The electrode according to claim 2, wherein the metal atoms are at least one of Zn and Cu.

18. The electrode according to claim 3, wherein the functional groups of the organic linkers are phosphonate and/or arsonate and/or monoester and/or diester forms thereof.

19. The electrode according to claim 4, wherein the auxiliary linkers comprise organoimine groups.

20. The electrode according to claim 4, wherein the organoimine groups are a Lewis base comprising a group 15 element.

21. The electrode according to claim 4, wherein the Lewis base is 4,4′-bipyridine.

Description

FIGURES

[0188] The invention is further described by the following figures. These are not intended to limit the scope of the invention, but represent preferred embodiments of aspects of the invention provided for greater illustration of the invention described herein.

[0189] Description of the figures:

[0190] FIG. 1: (A) One dimensional ladder type IBU of [{Cu.sub.2(4,4′-bpy).sub.0.5}(1,4-NDPA)] (1,4-NDPA is 1,4-naphthalenediphosphonate) (TUB-75) expanding. (B) The perspective view of rectangular void channels along with the top view of the one-dimensional IBU, where the band gap of the compound is 1.4 eV. (coloring; light blue is N, dark blue is Cu, yellow is P, red is O, black is C.) (C) The one dimensional inorganic building unit of [Co.sub.2(H.sub.4-MTPPA)].3NMP.H.sub.2O. The same pattern of IBU could be observed with other metal ions as well.

[0191] FIG. 2: Preferred examples of organic linkers of the MOFs of the invention comprising different geometrical cores. (A) V, (B) L, (C-D) T, (E-G) X, (H) Y shaped and (I) hexagonal linkers with extending tether arms, wherein X═C or Si; E═P or As; n=0,1,2 or 3; R═H, methyl, ethyl or isopropyl.

[0192] FIG. 3: (A) UV absorbance spectra and (B) tauc plot of [{Cu.sub.2(4,4′-bpy).sub.0.5}(1,4-NDPA)] (1,4-NDPA is 1,4-naphthalenediphosphonate) (TUB-75) samples creating band gap value of 1.4 eV.

[0193] FIG. 4: The picture of a section of the crystal structure of [{Cu(4,4′-bpy).sub.0.5(1,4-NDPA-H.sub.2)] where the one dimensional inorganic building unit composed of corner sharing Cu—O—P—O—Cu—O—P—O rings are connected by 1,4-napthalenediphosphonic acid and 4,4′-bipyridine. Hydrogen atoms are omitted for clarity.

[0194] FIG. 5: One dimensional inorganic building unit of three dimensional Zn.sub.2H.sub.4MTPPA MOF.

[0195] FIG. 6: Tauc Plot of [{Cu(H.sub.2O)}(2,6-NDPA).sub.0.5], which has a band gap value of 1.4 eV.

[0196] FIG. 7: Crystal structure of the two dimensional inorganic building of [{Cu(H.sub.2O)}(2,6-NDPA).sub.0.5] and attached 2,6-napthalenediphosphonate linkers between the layers.

[0197] FIG. 8: The Tauc Plot of [Zn{N(CH.sub.3).sub.2}(6-bromonapthalene-2-yl)phosphonate], which has a band gap value of 0.8 eV.

[0198] FIG. 9: Two dimensional inorganic building unit of [Zn{N(CH.sub.3).sub.2}(6-bromonapthalene-2-yl)phosphonate] and orientation of its organic components.

[0199] FIG. 10: Crystal structure and void channels of [Co.sub.2(H.sub.4-MTPPA)].3 NMP.H.sub.2O (NMP and water solvent molecules are omitted in the crystal structure).

[0200] FIG. 11: Spin-up and spin-down projected density of states for TUB75 in the AFM configuration. A) Copper. B) Carbon. C) Nitrogen. D) Phosphorous. E) Oxygen.

[0201] FIG. 12: Spin-up and spin-down projected density of states of the 1,4-NDPA and 4,4′-bpy carbons for TUB75 in the AFM configuration.

[0202] FIG. 13: Spin density isosurface of a portion of the IBU. beta/alpha spin density is shown in blue/red and corresponds to a difference between the spin-up and spin-down density of 0.005 electrons per Å.sup.3. Color definitions: O—red; N—orange; Cu—cyan; C—black; P—blue; H—white.

[0203] FIG. 14: a) Edge view of the rectangular void channel of GTUB-4. b) Perspective view of the rectangular void channel. c) Side-top view of tubular structure and its hexagonal sieves. d) Another side view facing the CuH.sub.4TPPA.sup.4− building unit with square void channels.

[0204] FIG. 15: a) b) and d) contain different views of the cross-packed GTUB-4 tubes in the crystal lattice. c) Cu—H.sub.4TPPA.sup.4− metal-binding modes with Ni.

[0205] FIG. 16: Estimation of the indirect band gap of GTUB-4 via Tauc plotting of the DRS spectrum.

[0206] FIG. 17: Impedance spectrum of TUB40 revealing purely Ohmic behavior with |Z|=179.3±0.2 mΩ between 0.1 Hz and ˜500 Hz. Above ˜500 Hz, |Z| and φ increase due to the increasing parasitic contributions from the connectors and cables in the setup.

[0207] FIG. 18: Spin-up (red arrow) and spin-down (blue arrow) projected density of states for TUB40 in the AFM configuration. (A) Carbon, (B) Copper, (C) Oxygen, (D) Phosphorous.

[0208] FIG. 19: Spin-up (red arrow) and spin-down (blue arrow) projected density of states for TUB40 in the AFM configuration, showing the contributions from p-orbitals of the carbon atoms (black) and d-orbitals of the copper atoms (cyan) with (A) an excess β-spin and (B) an excess α-spin.

[0209] FIG. 20: Spin-up (red arrow) and spin-down (blue arrow) projected density of states for TUB40 in the FM configuration. (A) Carbon, (B) Copper, (C) Oxygen, (D) Phosphorous.

[0210] FIG. 21: Spin-up (red arrow) and spin-down (blue arrow) projected density of states for TUB40 in the FM configuration, showing the contributions from p-orbitals of the carbon atoms (black) and d-orbitals of the copper atoms (cyan) with an excess α-spin.

[0211] FIG. 22: Indirect band gaps of A) Zn.sub.2(H.sub.4TPPA) (GTUB2) and B) Zn.sub.2(Cu—H.sub.4TPPA) (GTUB3).

[0212] FIG. 23: Crystal Structures of A) GTUB2 and B) GTUB3 respectively

[0213] FIG. 24: A) Comparison of the indirect band gap measurement of Cu.sub.3(H.sub.5-MTPPA).sub.2 (black line) and the linker MTPPA (red line) via Tauc plotting of UV-Vis spectra. B) Comparison of the direct band gap measurement of Cu.sub.3(H.sub.5-MTPPA).sub.2via and the linker MTPPA via Tauc plotting of UV-Vis spectra.

[0214] FIG. 25: a) The view of rectangular void channels in Cu.sub.3(H.sub.5-MTPPA).sub.2on ac plane b) The structure of the one-dimensional IBU in Cu.sub.3(H.sub.5-MTPPA).sub.2 c) The view of parallelogram void channes on the ab plane.

[0215] FIG. 26: Examples of phosphonic acid linkers with the fluorescein core. In these examples phenylphosphonic acids are linked to the fluorescein core.

[0216] FIG. 27: Examples of phosphonic acid linkers with the carbazole core.

[0217] FIG. 28: Example phosphonic acid linkers with aliphatic linkage between the aromatic core and the metal binding unit.

[0218] FIG. 29: Example of aliphatic or alkylene phosphonic acid and arsonic acid linkers, where R′ can be H, F, Cl, Br, I, NO.sub.2 and/or alkyl, aryl, phosphonic acid, alkyl phosphonic acids including methylphosphonic acid, ethylphosphonic acid, aryl-phosphonic acids, including phenylphosphonic acid, arsonic acids, alkyl arsonic acids including methylarsonic acid, ethylarsonic acid, aryl-arsonic acids, including phenylarsonic acid, phosphinates, aryl-phosphinates, and monoesters of the respective acid groups. Different R′ can be the same or different within one of the disclosed formulas. n can be any of the indicated number 1-15 or more.

EXAMPLES

[0219] The invention is further described by the following examples. These are not intended to limit the scope of the invention but represent preferred embodiments of aspects of the invention provided for greater illustration of the invention described herein.

[0220] The MOFs can be synthesized using the arylphosphonic acid or arylarsonic acid linkers presented in FIG. 2 and Tables 1 and 2 and their monoester forms. Such MOFs could be synthesized using hydrothermal, solvothermal reactions, conventional MOF reactions and also mechanochemistry could be used to synthesize such MOFs. Extended tether lengths of the linkers could be used to optimize the pore sizes. Using extended tethers could create MOFs with surface areas larger than 2000 m.sup.2/g. Using different metal ions could optimize the conductivity of the MOF while retaining the same framework structure.

[0221] The organic linkers presented in FIGS. 2 and Tables 1 and 2 can be synthesized via Suzuki Cross Coupling Method [Synthesis of Some Di- and Tetraphosphonic Acids by Suzuki Cross-Coupling, A. Schütrumph, A. Duthie, E. Lork, G. Yücesan and J. Beckmann, Z. Allgem. Anorg. Chem., 2018, 644 (19), 1134-1142]. The conventional, Pd and Ni catalyzed Arbuzov reactions can also be used to synthesize organophosphonic acid linkers. Arsonic acid analogues can also be synthesized using the same Suzuki Cross Coupline methodology and also using Bart Scheller Methods [Substituted phenylarsonic acids; structures and spectroscopy, N. C. Lloyd, H. W. Morgan, B. K. Nicholson, R. S. Ronimus, Journal of Organometallic Chemistry, 2008, 693, 2443-2450; The Preparation of Aromatic Arsonic and Arsinic Acids by the Bart, Bechamp, and Rosenmund Reactions, C. S. Hamilton, J. F. Morgan, In Organic Reactions; John Wiley & Sons, Inc., 2004; pages 415-454 (DOI:10.1002/0471264180.or002.10)].

[0222] We have measured the tauc plot of the compound [{Cu.sub.2(4,4′-bpy).sub.0.5}(1,4-NDPA)] (TUB75, example 2) (1,4-NDPA is 1,4-naphthalenediphosphonate) in FIG. 3A and B, which indicates that band gap of to be 1.4 eV. The tauc plot of compound [{Cu(H.sub.2O)}(2,6-NDPA)0.5] (TUB40, example 4) indicated that the band gap to be 1.4 eV. The Tauc Plot of compound [Zn{N(CH.sub.3).sub.2}(6-bromonapthalene-2-yl)phosphonate] indicated a band gap value of 0.8 eV.

Example 1

[0223] Conductive phosphonate-MOFs and arsonate-MOFs can be constructed around the organic molecules having at least one phosphonic acid or arsonic acid units in any geometrical orientation on the aromatic organic linker core. The conductive MOFs can be also constructed using any organic linker having at least one phosphonic acid monoester or arsonic acid monoester in any geometrical orientation around the organic scaffolds. The conductive phosphonate and arsonate-MOFs can be thermally stable up to 620° C.

[0224] The conductive MOFs can be synthesized using non limiting monovalent metal ions, Na.sup.+, Li.sup.+, Cs.sup.+, Cu.sup.+, Au.sup.+and Ag.sup.+, divalent Zn.sup.2+, Cu.sup.2+, Mg.sup.2+, Ba.sup.2+, Ca.sup.2+, Co.sup.2+, Ni.sup.2+, Cd.sup.2+ or trivalent Co.sup.3+, Al.sup.3+, Fe.sup.3+, Ti.sup.3+ or tetravalent Ti.sup.4+, Zr.sup.4+, V.sup.4+, Hf.sup.4+ with the organic linkers bearing phosphonic acid and arsonic acid metal binding groups.

[0225] Non-metal binding organic functional groups or elements such as halogens with different electronegativities can be covalently attached to the linker scaffold and such elements F, Cl, Br, I, or non-metal binding functional groups OH, NO.sub.2, or non-metal binding alkyl groups can be influential in optimizing the conductive behavior of the MOF.

[0226] Mechanochemistry can be used to synthesize the phosphonate and arsonate-MOFs in larger quantities.

Example 2

[0227] Phosphonate MOFs are known for their high structural diversity due to the multiple metal-binding modes and protonation states of the phosphonic acid group. They are known to contain complex molecular clusters and 1D/2D IBUs. Recently, Yücesan and co-workers synthesized the phosphonate MOF TUB75 (where TUB stands for Technische Universität Berlin) at temperatures above 180° C. and under hydrothermal reaction conditions [11]. As seen in FIG. 1a, the crystal structure of TUB75 shows the presence of copper dimer chains which were connected by fully deprotonated 1,4-naphthalenediphosphonic acid and 4,4′-bipyridine to give rectangular void channels. Full deprotonation leads to substantial electron delocalization within the 1D IBU. TUB75 has a calculated BET surface area of 132.1 m.sup.2/g. The thermal decomposition patterns of phosphonate MOFs constructed using 4,4′-bipyridine as the auxiliary linker with 1,4-naphthalenediphosphonic acid, 2,6-naphthalendiphosphonic acid, and different aromatic phosphonic acids were also previously reported.[11] MOFs in this family have a general tendency to be thermally stable up to ˜375° C., after which thermal decomposition begins. It was found for 2,6-naphthalendiphosphonic acid that removing the 4,4′-bipyridines to obtain pure metal phosphonates increases the thermal stability to ˜400° C. TUB75 crystals are transparent green colored needles.

[0228] The following example describes the synthesis of TUB75 that has experimental band-gap value of 1.4 eV and theoretically calculated band gap of 1.77 eV via DFT calculations. Band gap values of MOF crystals are obtained via Tauc Plotting of the UV spectra. The solid-state diffuse reflectance Ultraviolet-Visible (UV-vis) spectra of the synthesized MOF crystals of TUB75 have been collected on Varian Cary 300 UV-Vis Spectrophotometer. Tauc Plotting has indicated that TUB75 has band gap value of 1.4 eV, making it a semiconductor (see FIG. 3). In addition, we find that TUB75 possesses an antiferromagnetic chain-type IBU.

The Synthesis of 1,4-napthalenediphosphonic Acid

[0229] The synthesis of 1,4-napthalenediphosphonic acid follows the similar synthetic route for 2,6-naphthalenediphosphonic acid. The starting materials were purchased from Aldrich, TCl, ABCR and Alfa Aesar companies, and used as received. Naphthalene-1,4-diyl-bis(phosphonic diisopropyl ester) was obtained using a [Pd(PPh.sub.3).sub.4]-catalyzed Michaelis-Arbuzov reaction by conventional heating methods. A mixture of 1,4-dibromonaphthalene (1.0 g, 3.5 mmol), triisopropylphosphite (13.5 mL, 55 mmol) and [Pd(PPh.sub.3).sub.4] (38 mg, 0.016 mmol) was added in a 50 mL flask and heated to 200° C. under argon atmosphere (14 mL/min). After 1 h, reflux was started and the temperature was kept at 200° C. for 4 h. With the temperature constant at 200° C., triisopropylphosphite (4.0 mL, 16.2 mmol) and [Pd(PPh.sub.3).sub.4] (38 mg, 0.016 mmol) were added to the reaction flask as a second addition. After this addition, the temperature was increased to 220° C. and reaction was continued for 20 h. Upon fast cooling in a refrigerator, the white crystalline solid product was precipitated and filtered with a Gooch filter by washing with n-hexane.

[0230] Naphthalene-1,4-diylbis(phosphonic diisopropyl ester) (2.5 mmol) and 20 mL of HCl (37%) were added in a 50 mL flask and heated to 80° C. on a sand bath to synthesize 1,4-naphthalenediphosphonic acid. After 8 h, a white paste was obtained and this paste was treated with methanol to remove excess hydrochloric acid and isopropylchloride which is generated during acid-catalyzed hydrolysis. This methanol crude product mixture was evaporated under high vacuum and the solid final product was obtained as a white solid.

The Synthesis of [{Cu.SUB.2.(4,4′-bpy).SUB.0.5.}(1,4-NDPA)] (TUB75)

[0231] The hydrothermal reactions have been performed in 23 ml Teflon lined Parr Acid Digestion Vessels. The initial pH of the reaction mixture was recorded to be 2. 1,4-naphthalenediphosphonic acid (0.100 g, 0.35 mmol), CuSO.sub.4.5H.sub.2O (0.150 g, 0.60 mmol), 4,4′-bipyridine (4,4′-bpy) (0.040 g, 0.256 mmol) and water (10.084 g, 560 mmol) were mixed and this solution was maintained in closed 23 ml Teflon lined Parr Acid Digestion Vessel for 4 days at 200° C. under autogeneous pressure. After cooling to room temperature, the needle-shaped transparent green crystals were filtered, washed with acetone, and air-dried.

X-ray Data Collection and Structure Refinement Details

[0232] The crystal structure of TUB75 is shown in FIG. 1a and 1b. The solid-state structures of compound TUB75 was confirmed by X-ray diffraction analysis. The data was obtained with Bruker APEX II QUAZAR three-circle diffractometer. Indexing was performed using APEX2. Data integration and reduction were carried out with SAINT. TWINABS was used for absorption correction of TUB75. The structure was solved using Olex2, SHELXT and refined with the ShelXL refinement package using Least Squares minimization. CrystalMaker software was used to visualize the CIF file.

N.SUB.2 .adsorption isotherms and BET surface areas.

[0233] Grand canonical Monte Carlo (GCMC) simulations were performed to simulate the N.sub.2 adsorption isotherms of TUB75 at 77K and up to 0.4 bar.

Conductive and Magnetic Properties of TUB75

[0234] In FIG. 3B, an indirect Tauc plot derived from the UV-vis spectrum (shown in FIG. 3A) of a sample of pure handpicked (under a microscope) TUB75 crystals (thin green needles with an average length of 0.5 mm) is presented. Linear extrapolation of this Tauc plot yields an estimate of the optical bandgap of 1.4 eV, indicative of a semiconductor. To shed light on the origin of the semiconductivity, we performed DFT calculations. The density of states calculation yielded a HOMO-LUMO gap of E.sub.g =1.77 eV, which is in good agreement with the experimental bandgap of 1.4 eV. Based on the projected density of states (pDOS) in FIG. 11, we see that the HOMO-LUMO gap is predominantly due to atomic orbitals associated with the carbon atoms in the p-conjugated 1,4-naphthalenediphosphonic acid (1,4-NDPA) and 4,4′-bipyridine (4,4′-bpy) auxiliary linker groups. It also appears that there is some contribution from the nitrogen orbitals to the LUMO and a very small contribution from the oxygen orbitals to the HOMO. As for copper, there is effectively no contribution from the copper orbitals to the HOMO and LUMO. There is indication of spin dependence in the higher energy virtual orbitals, primarily associated with the copper atoms and smaller contributions coming from carbon, nitrogen, phosphorous, and oxygen. We further projected the carbon pDOS into the individual contributions from the 1,4-NDPA and the 4,4′-bpy carbons (FIG. 12). This projection reveals that the HOMO and LUMO are spatially separated, with the HOMO localized on the 1,4-NDPA carbons and the LUMO localized on the 4,4′-bpy carbons. In such a case, a photoexcited electron (in the LUMO) would be spatially separated from its hole (in the HOMO).

[0235] Electrical conductivity measurements on MOFs have been mainly based on polycrystalline pellets. However, such measurements may greatly underestimate the conductance of the MOF due to contact/grain boundary resistances and anisotropic electrical conduction. On the other hand, single-crystal measurements can provide much more accurate conductance values, provided that the crystals are large enough. Considering this, we carried out a number of single-crystal measurements on TUB75 by clamping the individual crystals between two gold surfaces of a relay. From room-temperature measurements, we obtained a range of resistances from 10 Ω to 10 MΩ, depending on the orientation of the crystal with respect to the gold surfaces. Assuming that the TUB75 crystal makes perfect contact with the gold surfaces, these resistances yield a maximum conductance of ˜10.sup.3 S m.sup.−1 and a minimum conductance of ˜10.sup.−3 S m.sup.−1. However, since the TUB75 crystals do not make perfect contacts with the gold surfaces, the actual conductance could even be higher than our reported values. Nevertheless, our results show that TUB75 is a semiconductor and provide strong evidence of the directional nature of the electrical conductivity of TUB75.

Conclusion

[0236] Herein, the conductive and magnetic properties of the phosphonate MOF TUB75 have been disclosed. With an experimental bandgap of 1.4 eV and room-temperature (orientation-dependent) conductance ranging from ˜10.sup.−3 to ˜10.sup.3 S m.sup.−1, TUB75 is the first semiconducting phosphonate MOF in the literature, paving the way for a new family of semiconductors with an extremely rich structural chemistry. The metal-binding modes of the phosphonic acid group in TUB75 support a 1D IBU composed of a zigzag copper dimer chain, which was found to be antiferromagnetically coupled. The temperature-dependent magnetic susceptibility data was well fit using a combination of a Heisenberg chain model at higher temperatures and Brillouin functions at very low temperatures. The experimental measurements were accompanied by DFT calculations, which yielded a bandgap of 1.77 eV in good agreement with the experimental one and support the AFM nature of the IBU. Given the high thermal/chemical stabilities of phosphonate MOFs and the numerous metal-binding modes of phosphonates, the disclose findings show that such MOFs can be used in next-generation electrodes and supercapacitors capable of withstanding harsh operating conditions. The vast structural diversity of phosphonate MOFs could lead to a new generation of porous materials with engineerable surface areas and magnetic/conductive properties.

Example 3

[0237] Arylphosphonic acid linkers could have intrinsic low band gap values. Once arylphosphonic acid linkers are connected with inorganic building units, they could form conductive MOFs. The following examples demonstrate the general formulation of phosphonate-MOFs constructed with one dimensional inorganic building unit composed of continuous corner or edge shared 8 membered M-O—P—O-M-O—P—O rings (M=a metal atom). M-O—P—O-M-O—P—O ring pattern can be present in two- and three-dimensional IBUs as well (See TUB40). For example, a one-dimensional IBU could be composed of tetrahedral Co atoms giving the one dimensional inorganic building unit as seen in FIG. 1c with Co—O—P—O—Co—O—P—O pattern. Changing the metal ion or organic linker identity could change the conformation of the one-dimensional IBU. Upon this conformational change, the surface area could change dramatically. For example, the 1034 m.sup.2/g surface area of Co.sub.2(H.sub.4-MTPPA)]3 NMP.H.sub.2O is substantially larger compared to the isostructural Zn.sub.2H.sub.4MTPPA and Zn.sub.2H.sub.4STPPA (MTPPA=methane tetra-p-phenylphosphonic acid and STPPA=silane tetra-p-phenylphosphonic acid). Both isostructural Zn.sub.2H.sub.4MTPPA and Zn.sub.2H.sub.4STPPA have one dimensional inorganic building unit composed of continuous corner or edge shared 8 membered Zn—O—P—O—Zn—O—P—O rings. Likewise, keeping the organic linker identity of TUB75 the same but changing the one-dimensional inorganic building unit to Cu—O—P—O—Cu—O—P—O ring pattern with square pyramidal Cu centers increases the surface area from 132.1 m.sup.2/g to 229.2 m.sup.2/g in [{Cu(4,4′-bpy).sub.0.5(1,4-NDPA-H.sub.2)] (1,4-NDPA-H.sub.2=di deprotonated 1,4-naphthalenediphosphonic acid). Due to the presence of 1,4-napthalenediphosphonic acid and one-dimensional inorganic building unit composed of Cu—O—P—O—Cu—O—P—O corner sharing rings, [{Cu(4,4′-bpy)0.5(1,4-NDPA-H.sub.2)] is also expected to show conductive behavior. Therefore, this working example includes the MOFs synthesized with one-dimensional inorganic building units composed of corner sharing 8 membered M-O—P—O-M-O—P—O rings, where M represents a metal ion. Experimental band gap estimation of Co.sub.2(H.sub.4-MTPPA)].3 NMP.H.sub.2O (H.sub.4-MTPPA is tetra deprotonated MTPPA linker) has given the 1.7 eV band gap value and initial DFT calculations gave an estimate of 1.15 eV band gap. As the MTPPA linker has a band gap value, which is above 4 eV, the formation of a one-dimensional IBU composed of continuous corner sharing 8 membered Co—O—P—O—Co—O—P—O rings is influential in generating low band gap MOF of Co.sub.2(H.sub.4-MTPPA)].3 NMP.H.sub.2O. The initial theoretical band gap calculations for MOFs Zn.sub.2H.sub.4MTPPA and Zn.sub.2H.sub.4STPPA (MTPPA=methane tetra-p-phenylphosphonic acid and STPPA=silane tetra-p-phenylphosphonic acid) also give an estimate of below 2 eV band gaps.

[0238] TGA analysis of [{Cu(4,4′-bpy).sub.0.5(1,4-NDPA-H.sub.2)] is performed using, TA instruments SDT Q600 series. Thermal decomposition of [{Cu(4,4′-bpy).sub.0.5(1,4-NDPA-H.sub.2)] starts at ca. 375° C. and decomposition continues until ca. 700° C.

The Synthesis of H.SUB.8.MTPPA (Methane Tetra-P-Phenylphosphonic Acid)

[0239] Under argon atmosphere, a mixture of tetrakis(tetrabromophenyl)methane (1.00 g, 1.57 mmol), triisopropylphosphite (12 mL, 48.6 mmol) and [Pd(PPh.sub.3).sub.4] (45 mg, 0.039 mmol) was heated under reflux for 4 h. After that time, another portion of triisopropylphosphite (4 mL, 16.2 mmol) and [Pd(PPh.sub.3).sub.4] (45 mg, 0.039 mmol) were added. The mixture was heated to to 220° C. for 20 h. Upon slow cooling, the white crystalline solid product precipitated that was filtered with a Gooch filter and washed with n-hexane (Yield; 1.37 g, 1.41 mmol, 89%).

[0240] .sup.1H-NMR (500 MHz, CDCl.sub.3) δ 7.72 (d, J=12.9, 8.3 Hz, 8H), 7.29 (d, 8H), 4.78-4.72 (m, 8H), 1.72 (s, 1H), 1.39 (d, J=6.2 Hz, 8H), 1.28 (d, J=6.2 Hz, 8H).

[0241] Tetraphenylmethane(phosphonic tetraisopropyl ester) (1.11 g, 1.14 mmol) was treated with 20 mL HCl (37%) on a sand bath at 80° C. for 24 h. Upon cooling, a colorless precipitate formed that was filtered and washed with methanol (10 mL). Drying afforded a colorless solid of 5a (Yield; 720 mg, 1.12 mmol, 98%).

[0242] .sup.1H NMR (500 MHz, CDCl.sub.3) δ 7.76 (d, 8H), δ 7.29 (d, 8H), 4.96 (m, 8H).

Synthesis of [Co.SUB.2.(H.SUB.4.-MTPPA)].3 NMP.H.SUB.2.O

[0243] Methane tetra-p-phenylphosphonic acid (H.sub.8-MTPPA) (0.100 g, 0.35 mmol), CoSO.sub.4.7 H.sub.2O (0.150 g, 0.60 mmol), and N-Methyl-2-pyrrolidone (NMP) (9 ml) were mixed and this solution was maintained in closed 23 ml teflon lined Parr acid digestion vessel for 24 hour at 165° C. under autogenous pressure. After cooling to room temperature, the dark blue block-shaped crystals were filtered, purified by hand picking under the microscope, washed with acetone, and air-dried.

[0244] X-ray data collection and structure refinement details for [Co.sub.2(H.sub.4-MTPPA)].3 NMP.H2O:

[0245] Data were obtained with Bruker APEX II QUAZAR three-circle diffractometer. Indexing was performed using APEX2. Data integration and reduction were carried out with SAINT. Absorption correction was performed by multi-scan method implemented in SADABS. The structure was solved using SHELXT and then refined by full-matrix least-squares refinements on F.sup.2 using the SHELX in OLEX All non-hydrogen atoms were refined anisotropically using all reflections with I>2 σ(I). Aromatic and aliphatic C-bound H atoms were positioned geometrically and refined using a riding mode. The P—OH hydrogen atoms were idealized and refined using rigid group (AFIX 147 option of the SHELXL program). The H atoms of water molecules were located in a difference Fourier map and their positions were constrained to refine on their parent O atoms with Uiso(H)=1.5 Ueq(O). Mercury and CrystalMaker was used for visualization of the cif file. See FIG. 10. TGA of Co.sub.2(H.sub.4-MTPPA)].3 NMP.H.sub.2O indicate that organic components from MTPPA linker start decomposing at ca. 525 C indicating exceptional thermal stability. The total weight loss of MTPPA continues until 700 C. The initial ca. 20% (calculated 27%) of weight loss in the TGA curve corresponds to the solvent molecules of NMP and H.sub.2O.

[0246] The BET surface area of Co.sub.2(H.sub.4-MTPPA)].3 NMP.H.sub.2O was derived from its simulated N.sub.2 adsorption isotherm at 77 K obtained by grand canonical Monte Carlo simulations. Such calculations have been widely used for characterizing the surface area of MOF materials. The calculated BET surface area for Co.sub.2(H.sub.4-MTPPA)].3 NMP.H.sub.2O is 1034 m.sup.2/g, which is 107 m.sup.2/g higher than its isostructural zinc compound Zn.sub.2H.sub.4-MTPPA. BET surface area of Zn.sub.2H.sub.4-MTPPA was measured to be 927 m.sup.2/g. The solvent molecules of NMP were omitted during the simulations.

[0247] Zn.sub.2H.sub.4MTPPA and Zn.sub.2H.sub.4STPPA are isostructural with Co.sub.2H.sub.4MTPPA with different bond lengths and angles in the inorganic building units.

Synthesis of Zn.SUB.2.H.SUB.4.MTPPA

[0248] A solution of ZnSO.sub.4.7H.sub.2O (200 mg, 0.69 mmol), H.sub.8-MTTPA (800 mg, 1.47 mmol) in dimethylformamide (10.0 mL, 129.7 mmol) was stirred briefly and heated to 180 C for 72 h in a PTFE-lined Parr acid digestion vessel. Tiny colorless crystals Zn.sub.2H.sub.4MTPPA were cleaned with acetone and air dried.

[0249] X-ray crystallography:

[0250] Intensity data were collected on Bruker Venture D8 diffractometers at 100 K with graphite-monochromated Mo-Kα (0.7107 Å) radiation. All structures were solved by direct methods and refined based on F.sup.2 by use of the SHELX program package as implemented in WinGX. All non-hydrogen atoms were refined using anisotropic displacement parameters. Hydrogen atoms attached to carbon atoms were included in geometrically calculated positions using a riding model. Hydrogen atoms attached to oxygen atoms were located in the last refinement cycle and refined isotropically. It should be noted that Platon/Squeeze procedure had to be used to account for diffuse electron density due to disordered solvent molecules. Crystal structure validations and geometrical calculations were performed using PLATON software. MERCURY and CrystalMaker softwares were used for visualization of the cif files. See FIG. 5.

[0251] BET surface area of 927 m.sup.2/g was derived from N.sub.2 adsorption isotherms at 77 K which were obtained by Monte Carlo simulations in the grand canonical ensemble.

Example 4

[0252] The following working example describes the synthesis of another phosphonate-MOF synthesized using 2,6-naphthalenediphosphonic acid (2,6-NDPA) as the linker. The band gap values of [{Cu(H.sub.2O)}(2,6-NDPA).sub.0.5] have been measured to be 1.4 eV using the tauc Plot derived from the UV data. See FIG. 6. The MOF [{Cu(H.sub.2O)}(2,6-NDPA).sub.0.5] is composed of a two dimensional inorganic building unit comprising copper dimers, which were connected to give the three dimensional structure of [{Cu(H.sub.2O)}(2,6-NDPA).sub.0.5]. See FIG. 7.

SUMMARY

[0253] We report a conductive phosphonate metal-organic framework (MOF), [{Cu(H.sub.2O)}(2,6-NDPA).sub.0.5] (TUB40) (NDPA=naphthalenediphosphonic acid), which contains a two-dimensional inorganic building unit (IBU) comprised of a continuous edge-sharing sheet of copper phosphonate polyhedra. The two-dimensional IBUs are connected to each other via polyaromatic 2,6-NDPA's, forming a three-dimensional pillared-layered MOF structure. This MOF, known as TUB40, has a narrow band gap of 1.4 eV and an average record high electrical conductivity of 200 S m.sup.−1 measured for single crystals of three-dimensional MOFs at room temperature and relative humidity while the pellet measurements produced 142 S/m conductance. For single crystals a conductivity of up to 10.sup.3 S m.sup.−1 was obtained. DFT calculations reveal that the conductivity is due to an excitation from the HOMO on the naphthalene building unit to the LUMO on the copper atoms. Temperature-dependent magnetization measurements show that the copper atoms are antiferromagnetically coupled at very low temperatures (which is also confirmed by the DFT calculations). Due to its high conductance and thermal/chemical stability, TUB40 represents an excellently suited material for electrodes in supercapacitors. TUB40 crystals retain their transparent color at 300° C.

The Synthesis of 2,6-Naphthalenediphosphonic Acid

[0254] Napthalene-2,6-dylbis(phosphonic diisopropyl ester) was obtained with [Pd(PPh.sub.3).sub.4] catalyzed Michaelis-Arbuzov reaction by conventional heating method. A mixture of 2,6-dibromonapthalene (1.0 g, 3.5 mmol), triisopropylphosphite (13.5 mL, 55 mmol) and [Pd(PPh.sub.3).sub.4] (38 mg, 0.016 mmol) was added on a 50 mL flask and heated to 200° C. under argon atmosphere (14 mL/min). After 1 h, reflux was started and temperature was kept at 200° C. for 4 h. While temperature was stable, triisopropylphosphite (4.0 mL, 16.2 mmol) and [Pd(PPh.sub.3).sub.4] (38 mg, 0.016 mmol) were added to the reaction flask as second addition. After this addition, temperature was increased to 220° C. and reaction was continued for 20 h. Upon fast cooling on refrigerator, the white crystalline solid product was precipitated and filtered with a Gooch filter by washing with n-hexane (Yield; 1.44 g, 91%). Spectral data: .sup.1H NMR (500 MHz, CDCl.sub.3) δ 8.47 (d, J=15.3 Hz, 5H), 8.00 (dd, J=8.4, 3.9 Hz, 5H), 7.89-7.80 (m, 5H), 7.27 (s, 2H), 4.99-4.62 (m, 12H), 1.76 (s, 6H). 1.15 g naphthalene-2,6-dylbis(phosphonic diisopropyl ester) (2.5 mmol) and 20 mL of HCl (37%) were added on a 50 ml flask and heated to 80° C. on a sand bath to synthesize naphthalene-2,6-dylbis(phosphonic acid). After 8 h, a white, paste-like mixture was obtained and this mixture was treated with methanol to remove excess hydrochloric acid and isopropylchloride which shows up during acidic hydrolysis reaction. This methanol-crude product mixture was evaporated under high vacuum and the solid final product was obtained as a white solid (Yield; 720 mg, 99%). Spectral data: .sup.1H NMR (500 MHz, CDCl.sub.3) δ 7.49 (s, 4H), 7.31 (d, J=19.1 Hz, 2H), 7.25 (s, 6H), 1.43 (s, 5H).

The Synthesis of [{Cu(H.SUB.2.O)}(2,6-NDPA).SUB.0.5.] (TUB40)

[0255] A mixture of CuSO.sub.4.5H.sub.2O (0.129 g, 0.52 mmol), napthalene-2,6-dylbis(phosphonic acid) (0.100 g, 0.35 mmol), and water (10.084 g, 560 mmol) were stirred gently and heated to 180° C. in a 23 ml Parr teflon lined stainless steel container under autogeneous pressure for 92 h. pH of the mixture was adjusted to 2 by adding sufficient amount of HNO.sub.3 After the reaction, the vessel was cooled to room temperature slowly and precipitate was filtered out by washing with distilled water and acetone. Green crystals of rectangular plates were air dried. Alternatively, it can be also synthesized at 200° C. using a mixture of CuSO.sub.4.5H.sub.2O (0.129 g, 0.52 mmol), napthalene-2,6-dylbis(phosphonic acid) (0.100 g, 0.35 mmol), and water (10.084 g, 560 mmol).

[0256] TGA analysis is performed using, TA instruments SDT Q600 series. Thermal decomposition of [{Cu(H.sub.2O)}(2,6-NDPA).sub.0.5] starts at ca. 400° C. and decomposition continues until ca. 850° C.

Experiments

[0257] We revisit the previously published MOF TUB40,[12] which is composed of two-dimensional sheets of corner-sharing copper and phosphorus polyhedra and explore its conductive and magnetic properties. In particular, we perform pellet conductivity, solid-state diffuse reflectance (to estimate the band gap via Tauc plotting), and temperature-dependent magnetization measurements.

[0258] Given the conductive nature of phosphorous and presence of d orbitals in P, it is presumed that the introduction of phosphonate groups throughout the copper oxide IBU promotes the semiconductivity in the two-dimensional IBUs. In addition, the use of organophosphonates with rich metal binding modes in the IBUs allows for optimizable surface areas, which could expand the range of semiconductor applications. Therefore, we sought to estimate the band gap of TUB40 from the UV-Vis diffuse reflectance spectrum of handpicked crystals of TUB40. As seen in FIG. 6, indirect Tauc plotting of the reflectance data reveals a band gap of 1.4 eV, which lies in the semiconductive range. Given the narrow bandgap, we then used impedance spectroscopy to measure the resistance of a 5 mm (diameter)×0.5 mm (thickness) TUB40 pellet at room temperature and calculated the resulting conductivity σ. This was done using a Zahner ZENNIUM impedance measurement unit in the potentiostatic mode (with 20 mV amplitude between 100 mHz and 100 kHz). To reduce the influence of contact resistance between the pellet surface and electrodes (stainless steel cylinders), the impedance measurement was done under a mechanical load of 1 MPa. In FIG. 17, the complex-valued impedance is displayed in the Bode representation in terms of the magnitude of the impedance, |Z|, and the phase shift, ϕ, between the input potential wave and measured current wave (NB: ϕ=0 for ohmic resistors and ϕ≠0 for serial or parallel combinations of capacitive, inductive, and resistive elements). From 0.1 Hz to −500 Hz, we see that |Z| and ϕ remain constant at 179.3±0.2 mΩ and 0°, respectively. This frequency independence is characteristic of pure ohmic resistors. Above ˜500 Hz, the plot exhibits a common feature of an impedance measurement setup, namely ϕ increases with increasing frequency towards 90° (here, 80° at 100 kHz). This artifact is caused by parasitic contributions from the connectors and cables, which lead to measurable inductances due to mutual induction or object- and wiring-inductance. Thus, frequencies with ϕ values higher than 1° were not considered in the calculation of the resistance, R, i.e., R was calculated from the mean |Z| between 0.1 Hz and 200 Hz. Finally, the conductivity, σ, was calculated to be σ=l/RA=5.Math.10.sup.−4m/0.1793Ω.Math.(0.25.Math.π.Math.(5.Math.10.sup.−3m).sup.2)=142 S m.sup.−1.

[0259] As measurements on polycrystalline pellets may greatly underestimate the conductance of the MOF due to contact/grain boundary resistances and anisotropic electrical conduction. The single crystal conductivity measurements of TUB40 yield a maximum conductance of ˜10.sup.3 S/m with an average of 200 S m.sup.−1. The averaged value might still rather underestimate of the real conductivity as crystals might have smaller contact surface area than actual crystal surface area when they contact the gold relays.

[0260] Density functional theory (DFT) calculations of the density of states (DOS), projected density of states (pDOS), band gap, band structure, and partial charges of TUB40 were also carried out.

[0261] The HOMO-LUMO gap was calculated to be 2.320 eV and, as seen in the pDOS (FIG. 18), the HOMO is predominantly dictated by the carbon orbitals of the naphthalenes and the LUMO by the orbitals on the copper and, to a lesser extent, the oxygen atoms. These results suggest that the AFM configuration has a spatially separated HOMO-to-LUMO transition. Further insight into the HOMO-LUMO gap is provided by the pDOSs in FIG. 19, which show the contributions from the p-orbitals of the carbons and the d-orbitals of the coppers with excess β- (FIG. 19A) and α-spins (FIG. 19B). As can be seen, the spin orientations of the copper d-orbitals contributing to the LUMO depend on the copper atom under consideration (i.e., a copper with an excess β-spin or α-spin). Specifically, for the coppers with the excess β/α-spins, spin-up/down electrons may populate the copper d-orbitals of the LUMO. Due to the electronic transition selection rule that ΔS=0 (i.e., the spin of the electron cannot change), the results suggest the possibility of excitations of spin-up/down electrons from the naphthalene π orbitals to the empty d-orbitals of copper atoms with unpaired spin-down/up electrons, i.e., a copper with an unpaired spin-up electron will only accept an excited spin-down electron into its empty d-orbitals and vice versa.

[0262] We next present and discuss the HOMO-LUMO gaps and pDOSs of the FM configuration. Based on the spin-up and spin-down band gaps, band structure, total DOS, and pDOS (FIG. 20), we see that the FM configuration's HOMO-LUMO gap is spin-dependent. More specifically, the spin-down states have a band gap of 2.195 eV, in the semiconductor regime, while the spin-up states have a band gap of 3.913 eV, which is closer to that of an insulator. This situation may be contrasted with that of a half-metal, where one spin orientation has a zero band gap and the other has a non-zero band gap. The HOMO is spin-independent while the LUMO is spin-dependent. To understand how the various atoms contribute to the spin-dependent HOMO-LUMO gap, we calculated the pDOS for carbon, copper, oxygen, and phosphorous shown in FIG. 20. The figure reveals that the HOMO of TUB40 in the FM configuration is predominantly dictated by the carbon orbitals of the naphthalenes (as in the case of the AFM configuration). On the other hand, the spin-down contribution to the LUMO is mainly composed of copper orbitals with a small contribution from the oxygen orbitals (as in the case of the AFM configuration), while the spin-up contribution is due to carbon orbitals. Based on these results, we see that the spin-down states have a spatially separated HOMO-to-LUMO transition (as in the case of the AFM configuration), while that of the spin-up states is localized on the naphthalene carbons. Further insight into the HOMO-LUMO gap is provided by the pDOS in FIG. 21, which shows the contributions from the p-orbitals of the carbons and the d-orbitals of the coppers with excess a-spins. As can be seen, spin-down electrons may populate the copper d-orbitals of the LUMO. Due to the electronic transition selection rule that ΔS=0, this figure suggests the possibility of excitations of spin-down electrons from the naphthalene π orbitals to the empty d-orbitals of the coppers, i.e., a β-spin π-d transition with a 2.195 eV gap.

[0263] Our smallest calculated HOMO-LUMO gaps (viz., 2.320 eV and 2.195 eV) are somewhat larger than the experimental estimate of the band gap (viz., 1.4 eV). This may indeed be the case as our gaps were calculated at 0 K, while the experimental gap was extracted from a UV-Vis spectrum obtained at room temperature. Moreover, given the low exchange energy at 0 K (viz., −1.50 meV), there may exist a mix of FM and AFM domains at higher temperatures. Finally, the results of the electronic population analyses show that the oxygens surrounding each copper atom have excess electron density (viz., for every three oxygens there is approximately an excess electron), pointing to high electron delocalization within the 2D IBU. The spin density isosurface of the AFM configuration shows that the spin density is delocalized onto the coppers and oxygens, suggesting that both of these atoms contribute to the magnetic behaviour of TUB40.

Example 5

[0264] This example is a two dimensional phosphonate-MOF [Zn{N(CH.sub.3).sub.2}(6-bromonapthalene-2-yl)phosphonate]. [Zn{N(CH.sub.3).sub.2}(6-bromonapthalene-2-yl)phosphonate] has a two dimensional inorganic building unit. [N(CH.sub.3).sub.2].sup.1− is the auxiliary ligand. [Zn{N(CH.sub.3).sub.2}(6-bromonapthalene-2-yl)phosphonate] forms white colorless transparent crystals. The band gap measurements from Tauc Plot curve has indicated that [Zn{N(CH.sub.3).sub.2}(6-bromonapthalene-2-yl)phosphonate] has a 0.8 eV band gap value. See FIG. 8. As seen in FIG. 9. [Zn{N(CH.sub.3).sub.2}(6-bromonapthalene-2-yl)phosphonate] has the eight membered Zn—O—P—O—Zn—O—P—O ring motifs connected to form the two dimensional IBU. Zn atoms are tetrahedral in the IBU.

[0265] (6-bromonapthalene-2-yl)phosphonic acid was synthesized following similar procedure to synthesize 2,6-napthalenediphosphonic acid via reducing the reaction time by half.

[0266] [Zn{N(CH.sub.3).sub.2}(6-bromonapthalene-2-yl)phosphonate] was synthesized after the solvothermal reaction of A solution of ZnSO.sub.4.7H.sub.2O (200 mg, 0.69 mmol), 6-bromonapthalene-2-yl)phosphonic acid (100 mg, 0.41 mmol) in dimethylformamide (10.0 mL, 129.7 mmol). White crystals of [Zn{N(CH.sub.3).sub.2}(6-bromonapthalene-2-yl)phosphonate] was washed with acetone and air dried.

[0267] X-ray diffraction data was obtained with Bruker APEX II QUAZAR three-circle diffractometer. Indexing was performed using APEX2. Data integration and reduction were carried out with SAINT. Absorption correction was performed by multi-scan method implemented in SADABS. The structure was solved using SHELXT and then refined by full-matrix least-squares refinements on F.sup.2 using the SHELX in OLEX All non-hydrogen atoms were refined anisotropically using all reflections with I>2σ(I). Aromatic and aliphatic C-bound H atoms were positioned geometrically and refined using a riding mode. The P—OH hydrogen atoms were idealized and refined using rigid group (AFIX 147 option of the SHELXL program). The H atoms of water molecules were located in a difference Fourier map and their positions were constrained to refine on their parent 0 atoms with Uiso(H)=1.5 Ueq(O). Mercury was used for visualization of the cif file (FIG. 9).

Example 6

[0268] A conjugated tetratopic linker, 5,10,15,20-tetrakis [p-phenylphosphonic acid]porphyrin (H.sub.8-TPPA), was used to synthesize a narrow band gap phosphonate MOF, namely [Ni(Cu—H.sub.4TPPA)].2(CH.sub.3)2NH.sub.2.sup.+ (GTUB-4), which has a unique one-dimensional microporous tubular structure with a very high geometric accessible surface area of 1102 m.sup.2/g and low indirect band gap of 1.90 eV.

The Synthesis of GTUB-4

[0269] The aim was to attain the simplest metal-binding modes with the tetratopic, structurally rigid, and planar phosphonic acid H.sub.8-TPPA (which contains a conjugated porphyrin core), whose phosphonic acid moieties are separated by −90° from one other. Thus, when H.sub.8-TPPA is coordinated to molecular IBUs in the simplest 1.100 mode (in Harris notation), they are expected to create square or rectangular void spaces. In this connection, the goal was to create H.sub.4TPPA.sup.4− (in which each phosphonate arm is mono-deprotonated) to achieve the 1.100 metal-binding mode. In addition, the aim was to create an extended one-dimensional conjugated system that facilitates the conduction of electrons. To achieve this, a low-temperature synthesis in DMF was performed to promote the formation of molecular IBUs, as a high-temperature hydrothermal synthesis could provide enough energy to form one-dimensional or two-dimensional IBUs. Furthermore, in a square planar coordination environment, the high energy d.sup.9 electrons of Cu(II) can support conductive behavior in MOFs. Inside a porphyrin core, Cu(II) usually adopts a square planar coordination environment. Therefore, the Pd-catalyzed Arbuzov reaction was adapted to synthesize metal-free H.sub.8-TPPA. Due to the large ionic radius of the Pd atom, it does not readily incorporate into the porphyrin ring, allowing one to incorporate other metal atoms into the porphyrin core. Later, square planar Cu(II) was introduced into H.sub.8-TPPA's pyrole ring to synthesize Cu-H.sub.8TPPA (the deprotonated pyrole hydrogens are omitted in this formula). GTUB-4 was synthesized in a DMF/H.sub.2O and phenylphosphonic acid (modulator) mixture at 80° C. for 24 h, giving rise to long dark red needle-like crystals in high yield. These carefully controlled conditions were required to achieve the simplest 1.100 phosphonate metal-binding modes.

[0270] The structure of GTUB-4 was solved using X-ray crystallography. As seen in FIG. 14, GTUB-4 has a one-dimensional tubular structure. Each tube consists of a central rectangular void channel (see FIGS. 15a and 15b) and two different hexagonal voids on the sides, top, and bottom of the tube (see FIGS. 1c and 1d). The phosphonate metal-binding groups in GTUB-4 have 1.100 metal-binding modes (the simplest type of metal-binding mode), where a Ni(II) atom forms two coordinate covalent bonds and two ionic bonds with the phosphonate groups of the H.sub.8TPPA linker. As mentioned earlier, this was achieved under well-controlled pH, temperature, and solvent conditions—the three variables that can be tuned to explore the large structural space of phosphonate MOFs. The presence of dimethylammonium cations and the acidic nature of GTUB-4 suggest that increasing the basicity of GTUB-4's environment could lead to further deprotonation of the phosphonic acids and, in turn, variations in the structure and properties. The crystal structure of GTUB-4 reveals that it contains a simple IBU, namely octahedral nickel metal centers coordinated to the four phosphonic acid metal-binding groups of H.sub.8-TPPA. As seen in FIGS. 15A and 15B, the basal plane of octahedral Ni exclusively connects the Cu—H.sub.4TPPA.sup.4− linkers, while the apical positions of Ni are occupied by two water molecules. Furthermore, as seen in FIGS. 16A, B and C, GTUB-4's nanotubes are held together via hydrogen bonds with the water molecules located at the apical positions of the octahedral Ni(II). Therefore, GTUB-4 can also be viewed as a three-dimensional hydrogen-bonded framework constructed from one-dimensional MOF nanotubes. FIG. 15D shows that the two distinct MOF nanotubes are packed at 41.87° relative to each other, leading to growth in two different directions. As the tubular structure of GTUB-4 is composed of three distinct pore sites (see FIGS. 16A, 16C, and 16D), the textural properties of GTUB-4 were characterized with molecular simulations. The calculations yielded a specific pore volume of 0.425 cm.sup.3/g, a geometric accessible surface area of 1102 m.sup.2/g, and pores of −5 Å in diameter.

[0271] The structure of GTUB-4 shown in FIG. 14D suggests that H.sub.8-TPPA's conjugation extends over the mono-deprotonated tetrahedral phosphonate metal-binding unit R—P=O(OH)O.sup.−1, in which the phosphonate electrons could delocalize over the tetrahedral geometry. In light of these results, solid-state diffuse reflectance spectroscopy (DRS) were used to estimate the optical band gap of GTUB-4 (see FIG. 16). The indirect optical band gap of GTUB-4 was found to be 1.9 eV. The narrowness of the band gap is likely due to the extended conjugation mediated by the mono-deprotonated phosphonate metal-binding unit.

[0272] The presence of metal ions typically increases the thermal stability of MOFs compared to that of the linkers due to the additional covalent and ionic bonding opportunities in MOFs. Thus, we studied the thermal behaviors of H.sub.8-TPPA, Cu—H.sub.8TPPA, and GTUB-4 via thermogravimetric analysis (TGA). The TGA curve obtained under N.sub.2 from the hand-picked GTUB-4 crystals indicates that the solvent and water molecules evaporate from GTUB-4 until 100° C. The second step of −11.1% weight loss corresponds to the evaporation of dimethylammonium cations in the crystal lattice (12.3% calculated). The third step of −28.8% weight loss between −400° C. and −650° C. corresponds to the evaporation of nearly half of the organic components of H.sub.8TPPA (52% calculated). The decomposition of GTUB-4 continues above 900° C., suggesting that GTUB-4 might be converted into thermally stable phosphides above 650° C.

Conclusion

[0273] GTUB-4 is a nanotubular MOF, which was constructed using the highly conjugated H.sub.8-TPPA linker. The strict pH and temperature control enabled the formation of a one-dimensional tubular structure with a geometric accessible surface area of 1102 m.sup.2/g. The conjugated porphyrin core and electron delocalization around the phosphonate metal-binding unit are enhances the conjugation along the 1D structure. This results in a narrow band gap of 1.9 eV identifies GTUB-4 as a semiconductor. We were able to selectively introduce square planar Cu(II) with high energy electrons into the porphyrin core of GTUB-4, where the linker connectivity is achieved via octahedral Ni centers. The thermal decomposition pattern of GTUB-4 indicates that it is thermally stable up to 400° C., after which the organic components of the porphyrin core decompose. The presence of water at the apical position of the octahedral Ni site suggests the possibility of post-synthetic modifications of GTUB-4. Due to its narrow band gap and high surface area, GTUB-4 is ideally suited as an electrode material in the next generation of supercapacitors.

[0274] An isostructural cobalt version of GTUB4 has been synthetized and highly similar properties as reported here for GTUB-4 could be confirmed.

Example 7

[0275] Two further three-dimensional zinc metal organic frameworks have been constructed using H.sub.8TPPA linkers and Cu(H.sub.8TPPA) linkers (copper atom is located in the pyrolle ring of H.sub.8TPPA), respectively. Crystals of Zn.sub.2(H.sub.4TPPA) (GTUB2) and Zn.sub.2(Cu—H.sub.4TPPA) (GTUB3) have indirect bandgaps with in the semiconductive region of ca. 1.66 eV and 1.64 eV respectively, as evident from the measurements and results depicted FIG. 22. The inorganic building unit of these two zinc MOFs comprise tetrahedral zinc atoms, as shown in the crystal structures of FIG. 23.

Example 8

[0276] This example discloses another Cu-MOF: Cu.sub.3(H.sub.5-MTPPA).sub.2. Cu.sub.3(H.sub.5-MTPPA).sub.2 is synthesized with the MTPPA (methane-p-tetraphenylphosphonic acid) linker producing one dimensional inorganic building unit composed of edge sharing 8 membered Cu—O—P—O—Cu—O—P—O rings (see FIG. 24). As it can be seen in direct and indirect band gap figures the organic components MTPPA has above 4 eV band gap but as the copper MOF is formed, the band gap is reduced below 2.5 eV within the semiconductive regime. It seems like presence of an 8 membered Cu—O—P—O—Cu—O—P—O ring or 8 membered M-O—P—O-M-O—P—O rings (where M is a metal ion) in 1D, 2D and 3D IBUs enhance the semiconductive behaviour.

[0277] The presence of an unpaired electron in the square-planar d.sup.9 Cull centers indicates the presence of high energy electrons in the one-dimensional IBU of Cu.sub.3(H.sub.5-MTPPA).sub.2. Therefore, we have further decided to follow up the conductive nature of this novel phosphonate-MOF. The initial band gap measurements obtained from indirect and direct Tauc plot graphs, which were derived from the UV-Vis spectra generates a typical semiconductor jump at 2.4 eV and 2.7 eV respectively. The center of the H.sub.5MTPPA has an insulating sp.sup.3 methane core, which could inhibit the conductive behavior. As seen in FIG. 24, we have further tested the band gap of H.sub.8MTPPA to be 4.2 eV, which is not close to the semiconductive region and this band is not seen in Cu.sub.3(H.sub.5-MTPPA).sub.2's Tauc plot as a second jump. Therefore, the low band gap of Cu.sub.3(H.sub.5-MTPPA).sub.2 is associated with the resulting MOF structure or the presence of 1D IBU composed of 8 membered Cu1-O—P—O—Cu1-O—P—O and Cu2-O—P—O—Cu2-O—P—O rings with the presence of high energy square planar Cu(II) d.sup.9 electrons. The presence of square planar copper centers in the IBU of Cu.sub.3(H.sub.5-MTPPA).sub.2 could further help the semiconductive band gap observed in the indirect Tauc plot.

[0278] The crystal structure of Cu.sub.3(H.sub.5-MTPPA).sub.2 (FIG. 25) indicates two different type of square shaped and parallelogram shape void channels. The Monte Carlo simulations predict the surface area of Cu.sub.3(H.sub.5-MTPPA).sub.2to be 766.2 m.sup.2/g.

Synthesis of Cu.SUB.3.(H.SUB.5.-MTPPA).SUB.2

[0279] Methane-p-tetraphenylposphonic acid (MTTPA) (40 mg, 0.062 mmol), CuSO.sub.4.5H.sub.2O (30 mg, 0.120 mmol) and N-Methyl-2-pyrrolidone (NMP) (8 mL) were mixed and sonicated. Then this mixture was heated up in closed PTFE vessel for 24 hours at 168° C. under autogenous pressure. After slowly cooling to room temperature, the transparent light blue/green block-shaped crystals were filtered and washed with acetone. A pure single crystal phase was collected.

References

[0280] 1. Conway, B. E. Electrochemical Supercapacitors: Scientific Fundamentals and Technological Applications. Plenum Press, 1999.

[0281] 2. Robust and conductive two-dimensional metal-organic frameworks with exceptionally high volumetric and areal capacitance. Feng, D.; Lei, T.; Lukatskaya, M. R.; Park, J.; Huang, Z.; Lee, M.; Shaw, L.; Chen, S.; Yakovenko, A. A.; Kulkarni, A.; Xiao, J.; Fredrickson, K.; Tok, J. B.; Zou, X.; Cui, Y.; Bao, Z. Nat Energy 2018, 3, 30-36.

[0282] 3. Materials for electrochemical capacitors. Simon, P.; Gogotsi, Y. Nat Mater 2008, 7, 845-854.

[0283] 4. Carbons and electrolytes for advanced supercapacitors. Böguin, F.; Presser, V.; Balducci, A.; Frackowiak, E. Adv Mater 2014, 26, 2219-2251.

[0284] 5. Review of nanostructured carbon materials for electrochemical capacitor applications: advantages and limitations of activated carbon, carbide-derived carbon, zeolite-templated carbon, carbon aerogels, carbon nanotubes, onion-like carbon, and graphene. Gu, W.; Yushin, G. WIREs Energy Environ 2014, 3, 424-473.

[0285] 6. Energy storage applications of activated carbons: supercapacitors and hydrogen storage. Sevilla, M.; Mokaya, R. Energy Environ Sci 2014, 7, 1250-1280.

[0286] 7. The Chemistry and Applications of Metal-Organic Frameworks. Furukawa, H.; Cordova, K. E.; O'Keeffe, M.; Yaghi, O. M. Science 2013, 341, 974.

[0287] 8. Supercapacitors of Nanocrystalline Metal-Organic Frameworks. Choi, K. M.; Jeong, H. M.; Park, J. H.; Zhang, Y.-B.; Kang, J. K.; Yaghi, O. M. ACS Nano 2014, 8, 7451-7457.

[0288] 9. Conductive MOF electrodes for stable supercapacitors with high areal capacitance. Sheberla, D.; Bachman, J. C.; Elias, J. S.; Sun, C.-J.; Shao-Horn, Y.; Dinca, M. Nat Mater 2017, 16, 220.

[0289] 10. Metal-organic solids derived from arylphosphonic acids. Yücesan, G.; Zorlu, Y.; Stricker, M.; Beckmann, J. Coordin Chem Rev 2018, 369, 105-122.