ORGANOGEL BASED ON MOLECULES DERIVED FROM 7,7'-DIAZAISOINDIGO

Abstract

The invention relates to: a compound derived from 7,7-diazaisoindigo; an organogel, formed by these compounds, having an aggregation-induced emission (AIE) in the red region of the visible spectrum (600-800 nm); and a xerogel produced by drying said organogel. Due to these properties, said organogel or xerogel can be applied to optoelectronic devices or fluorescent sensors.

Claims

1. A compound of formula (I): ##STR00004## where Y is selected from CH.sub.2, O, NH, C(O), S, S(O), NHC(O), (O)CNH and R.sub.1 is a C.sub.1-C.sub.12 alkyl.

2. The compound, according to claim 1, where Y is CH.sub.2.

3. The compound, according to claim 2, where R.sub.1 is a C.sub.3-C.sub.11 alkyl.

4. The compound, according to claim 3, where R.sub.1 is a heptyl.

5. The compound, according to claim 1, having the following formula: ##STR00005##

6. (canceled)

7. An organogel, comprising at least one compound of formula (I) according to claim 1, characterised in that it emits fluorescence at a wavelength between 600 and 800 nm.

8. A xerogel, characterised in that it is the dessicated organogel according to claim 7.

9. A device comprising the xerogel according to claim 8.

10. (canceled)

11. (canceled)

12. A fluorescent material comprising the compound of formula (I) according to claim 1.

13. The device according to claim 9, wherein the device is an optoelectronic device or a fluorescent sensor.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0022] FIG. 1. a) Image of the organogel obtained from compound 1 (at 2.75% w/w) in cyclohexane at room temperature and following the inverted tube procedure b) SEM images of a dried gel of 1 in cyclohexane.

[0023] FIG. 2. Absorption 1 in cyclohexane 210.sup.5 M.

[0024] FIG. 3. Emission spectrum of 1 (.sub.exc=328 nm) in cyclohexane, the continuous line is (210.sup.4 M), the dashed line is the gel at 4.610.sup.2 M in cyclohexane.

[0025] FIG. 4. Emission spectrum of the gel state and sol state of 1 at different temperatures in cyclohexane.

[0026] FIG. 5. Optical microphotograph of the crystals obtained upon cooling hot acetone.

[0027] FIG. 6. Packed crystallographic structure of compound 1

[0028] FIG. 7. .sup.1H NMR spectrum of 1 in CDCl.sub.3.

[0029] FIG. 8. .sup.130 NMR spectrum of 1 in CDCl.sub.3.

EXAMPLES

[0030] The invention is illustrated hereunder by means of assays that demonstrate the effectiveness of the product of the invention.

Example 1

Synthesis of Compound (1)

[0031] The synthesis of N-dioctyl 7,7-diazaisoindigo (1, Scheme 1) was carried out by means of the alkylation of 7,7-diazaisoindigo by means of 1-iodooctane in the presence of K.sub.2CO.sub.3 and DMF at 100 C. for 16 hours.

##STR00003##

[0032] A mixture of 7,7-diazaisoindigo (25 mg, 0.09 mmol), 1-iodooctane (0.04 ml, 0.21 mmol) and K.sub.2CO.sub.3 (39.2 mg, 0.28 mmol) in 2 ml of DMF was heated to 100 C. for 16 hours. The red solution was dissolved in CH.sub.2Cl.sub.2, washed with water and dried with anhydrous MgSO.sub.4. The solvent was evaporated and the residue was chromatografied on the silica gel (hexane:acetone, 5:1) to give a red solid (1) (30 mg, 65%):

[0033] (E)-1,1-dioctyl-[3,3-bipyrrolo[2,3-b]pyridinylidene]-2,2(1 H,1H)-dione (1): .sup.1H NMR (200 MHz, CDCl.sub.3,) 9.46 (d, J=8 Hz, 2H), 8.24 (d, J=8 Hz, 2H), 7.02 (dd, J=8 Hz, 2H), 3.90 (t, J=7.5 Hz, 4H), 1.76 (m, 4H), 1.24 (m, 20H), 0.87 (t, J=6.5 Hz, 6H); .sup.13C NMR (50 MHz, CDCl.sub.3) 167.6, 157.7, 150.2, 137.5, 132.3, 118.4, 116.1, 39.4, 31.8, 29.2, 29.2, 27.8, 27.0, 22.6, 14.1; UV-vis (CH.sub.2Cl.sub.2, 25 C.) .sub.max () 283 (30690), 327 (12034), 477 (5069); MALDI-TOF MS m/z 489 (M.sup.+); HRMS (MALDI-TOF) calculated for C.sub.30H.sub.40N.sub.4O.sub.2: 489.3224, found: 489.3240.

Example 2

Synthesis and Study of the Organogel Properties Based on Compound (1)

[0034] In order to obtain the organogel based on compound (1), the powder of this compound was dissolved (at 2.75% w/w) in cyclohexane, used as an apolar solvent, by heating, forming non-fluid gel-type materials after cooling. Additionally, this organogel of 1 is opaque and red in colour, wherein the sol-gel interconversion cycle was assayed by means of the inverted tube procedure (FIG. 1a).

[0035] In order to obtain a visual understanding of the aggregation, the morphology of the dried gel (xerogel) was microscopically examined by means of field emission scanning electron microscopy (FE-SEM) (FIG. 1b). The xerogel of 1, prepared by means of slow cyclohexane evaporation in the gel state, was not homogeneous and long fibres were easily found inside the films (FIG. 1b). In the SEM analysis, the gel was transferred to a silicon substrate and the solvent was slowly evaporated again to give a xerogel.

[0036] The spectroscopic characterisations of 1 both in solution and in solid state were studied. The electronic absorption spectrum of 1 in cyclohexane showed three absorption bands in 280, 327, 470 nm (10.sup.5 M) (FIG. 2). The absorption band of the xerogel 1 in film on quartz slides showed three absorption bands at 287, 329 and 507 nm, with a broader band absorption spectrum in comparison to the solution state. The absorption spectrum of the xerogel in film state is more batochromically shifted compared to that in a solution state, presumably due to the increased intermolecular interactions between neighbour molecules in the solid state.

[0037] The fluorescence spectrum of 1 in a cyclohexane solution (210.sup.A M) showed two bands, with a maximum at 392 and 618 nm (.sub.exc=328 nm). However, compound 1 at 4.610.sup.2 M in cyclohexane forms an organogel, which emits in the red region of the spectrum with a batochromic shift with respect to the diluted solution, which shows a typical AIE characteristic. (FIG. 3). However, when this organogel is heated in cyclohexane, it can be observed how its emission in gel state is eliminated, observing that it is scarcely fluorescent in the sol state (FIG. 4). The gel-sol state transition is between 40-45 C.

[0038] Therefore, it is conjectured that the supramolecular organogel gelation and formation process induced an aggregation-induced emission phenomenon (AIE). Said AIE behaviour was found during sol-gel phase transition.

[0039] Moreover, the emission spectrum of the xerogel of 1, obtained from the gel state in cyclohexane, also exhibits a considerable batochromic shift compared to the solution diluted in cyclohexane. The xerogel of 1 exhibits an emission band at approximately 610 nm (.sub.exc=470 nm). The xerogel of 1 also emits fluorescence in the red region of the spectrum in its films in the solid state. This data is significant taking into account that most luminophoric materials are used as solid films due to their practical applications. Therefore, the xerogel of 1 could be used to build fluorescent sensors.

[0040] In order to better understand the fluorescent properties and interactions, various experiments on dependence on the concentration of .sup.1H in RMN were conducted, using cyclohexane-d.sub.12 as a deuterated solvent, demonstrating that the formation of organogellants occurs by means of very weak - type interactions, since a slight shift of the aromatic signals was observed.

[0041] X-ray diffraction (XRD) has great potential for elucidating the molecular structure of the organogels and can provide information on molecule assembly in the gel phase. XRD of the cyclohexane xerogel (2.75% by weight) has four reflections, three of which in the low angle region in 18.01, 9.00 and 6.00, with a laminar packing ratio corresponding to planes (001), (002) and (003).

[0042] Furthermore, the crystalline structure of 1 was dissolved in acetone/dichloromethane (Table 1, Table 2, FIGS. 4, 5 and 6). Reddish crystals of 1 were obtained, adequate for single-crystal X-ray analysis, from slow evaporation in acetone/dichloromethane. The X-ray analysis indicates that species 1 crystallises in the monoclinic spatial group P2.sub.1/c

TABLE-US-00001 TABLE 1 Crystal 1 data Chemical formula C.sub.30H.sub.40N.sub.4O.sub.2 Molecular weight 488.66 Temperature 296(2) K Wavelength 0.71073 Crystal size 0.04 0.18 0.24 mm Crystal habit Light red plate Crystalline system monoclinic Spatial group P2.sub.1/c a = 18.7376(11) = 90 b = 4.8671(3) = 106.762(2) Unit cell dimensions a = 18.7376(11) = 90 b = 4.8671(3) = 106.762(2) c = 15.8639(8) = 90 Volume 1385.28(14) .sup.3 Z 2 Density (calculated) 1.172 Mg/cm.sup.3 Absorption coefficient 0.074 mm.sup.1 F(000) 528

TABLE-US-00002 TABLE 2 Refining data of structure 1 Theta range for the data 2.27 to 25.35 collected Ranges of hkl indices 22 <= h <= 17, 5 <= k <= 5, 18 <= l <=18 Reflections collected 14003 Independent reflections 2493 [R(int) = 0.0506] Coverage of independent 98.7%. reflections Absorption correction multi-scanning Max. and min. transmission 0.9970 and 0.9824 coefficient Structure solution technique Direct methods Structure solution program SHELXS-97 (Sheldrick, 2008) Refinement method full-matrix least square on F.sup.2 method Refinement program SHELXL-97 (Sheldrick, 2008) Minimised function w(Fo.sup.2 Fc.sup.2).sup.2 Data/Restrictions/Parameters 2493/0/165 Goodness-of-fit on F.sup.2 1.056 / max 0.001 Final R indices 1569 data; I > 2(I) R1 = 0.0564, wR2 = 0.1270 All data R1 = 0.1045, wR2 = 0.1618 Weighting scheme w = 1/[.sup.2(F.sub.o.sup.2) + (0.0925P).sup.2 + 0.0000P] where P = (F.sub.o.sup.2 + 2F.sub.c.sup.2)/3 Positive and negative peaks 0.392 and 0.337 e.sup.3 of greatest magnitude Greatest R.M.S deviation 0.147 e.sup.3

[0043] The monocrystalline structure of 1 revealed the planarity of the core and a significant intermolecular interaction between adjacent platforms. The crystals of compound 1 formed crystals in the form of very thin fibres. Compound 1 crystallises in the monoclinic spatial group P2.sub.1/c. Only one half of the molecule in the asymmetrical unit, with an inversion centre disposed in the centre. The central ring is completely flat; coupling of the molecules in the crystal is achieved by means of - interactions that give rise to stair columns parallel to the b direction, where the adjacent molecules at a distance of 3.335 , with a slip angle of 43.28. The slip angle is calculated as the angle between the long axis of a molecule and the centre line of adjacent molecules in the column. The packing of the columns in the crystal showed that the neighbour columns are inclined in the same direction as the angle, while molecule cores in adjacent columns in the c direction show a nearly perpendicular angle of 86.52.