Electrochromic single and two-core viologens and optical articles containing them

Abstract

The present invention relates to a group of novel electrochromic materials. More specifically, it relates to electrochromic materials based on either single or two-core viologen systems and the use of these viologen systems as a variable transmittance medium for the manufacture of an optical article, such as an ophthalmic lens.

Claims

1. A compound of formula (I): ##STR00063## wherein: Z is selected from: alkylene; cycloalkylene; and a bivalent groups of formula —R.sup.7—Y—R.sup.8—, wherein R.sup.7 and R.sup.8 are each independently selected from single bond, alkylene and cycloalkylene, and Y is selected from arylene, cycloalkylene, heteroarylene, arylene-arylene or arylene-CR′R″-arylene wherein R′ and R″ form together with the carbon to which they are linked a carbocyclic group; wherein said alkylene, cycloalkylene, arylene, heteroarylene and carbocyclic groups may be substituted by one or more substituents selected from halogen, alkyl, alkoxy, alkylthio, hydroxyalkyl, acyloxy, cycloalkyl, aryl, substituted aryl, aryloxy, heteroaryl and substituted heteroaryl; wherein said alkylene, cycloalkylene, arylene, heteroarylene and carbocyclic groups may be substituted by one or more substituents selected from halogen, alkyl, alkoxy, alkylthio, hydroxyalkyl, acyloxy, cycloalkyl, aryl, substituted aryl, aryloxy, heteroaryl and substituted heteroaryl; m is 0 or 1; R.sup.1 and R.sup.2 are each independently selected from optionally substituted phenyl of formula (II): ##STR00064## wherein R.sub.a, R.sub.b, R.sub.c, R.sub.d and R.sub.e are each independently selected from: H, halogen, cyano, nitro, alkyl, haloalkyl, haloalkoxy, (haloalkoxy)alkyl, arylalkyl, cycloalkyl, (cycloalkyl)alkyl and (heterocycloalkyl)alkyl, alkenyl, alkynyl, allyl, vinyl, aryl, substituted aryl, heteroaryl, substituted heteroaryl, —N(aryl).sub.2, —N(aryl)CO(aryl), —CO-aryl and —CO-substituted aryl; —OR.sup.9, —SR.sup.9, —S(O)R.sup.9, —S(O.sub.2)R.sup.9, —S(O.sub.2)NR.sup.9R.sup.10, —NR.sup.9R.sup.10, —NR.sup.9COR.sup.10, —NR.sup.9CO(aryl), —NR.sup.9aryl, —CH.sub.2OR.sup.9, —CH.sub.2SR.sup.9, —CH.sub.2R.sup.9, —CO—R.sup.9 and —CO.sub.2R.sup.10 wherein R.sup.9 and R.sup.10 are independently selected from H, alkyl, haloalkyl, arylalkyl, cycloalkyl, cycloalkylalkyl and heterocycloalkylalkyl; —S(O.sub.2)NR.sup.11R.sup.12 and —NR.sup.11R.sup.12, wherein R.sup.11 and R.sup.12 form together with the nitrogen atom to which they are linked a saturated 5 to 7 membered heterocycloalkyl which may comprising in addition to the nitrogen atom one further heteroatom selected from oxygen, nitrogen and sulfur, and which may be optionally substituted by one or two groups, identical or different, selected from halogen, —R.sup.9, —OR.sup.9, and —NR.sup.9R.sup.10, wherein R.sup.9 and R.sup.10 are as defined above; —V—W—R.sup.13 wherein: V is selected from oxygen, —N(R.sup.9)—, sulfur, —S(O)— and —S(O.sub.2)— wherein R.sup.9 is as defined above; W is alkylene, which may be substituted by a group selected from halogen and alkoxy; and R.sup.13 is selected from —OR.sup.9, —NR.sup.9(alkyl) and —SR.sup.9 wherein R.sup.9 is as defined above; and OC(O)—R.sup.14 wherein R.sup.14 is selected from alkyl, haloalkyl, alkenyl, —W—R.sup.13, and aryl group which may be substituted by 1 to 4 groups selected from halogen, —R.sup.9, —OR.sup.9, —SR.sup.9, —NR.sup.9R.sup.10, —NR.sup.11R.sup.12, —CO—R.sup.9, —CO.sub.2R.sup.9 wherein R.sup.9, R.sup.10, R.sup.11, R.sup.12, R.sup.13 and W are as defined above, with the provisions that: when Y is arylene-arylene or arylene-alkylene-arylene, then R.sup.1 and R.sup.2 are not phenyl; when m is 0, then R.sub.e is H and at least one of R.sub.a, R.sub.b R.sub.c and R.sub.d is not H and may be independently selected from cyano, nitro, hydroxyl, C.sub.4-C.sub.12 alkyl, haloalkyl, alkoxy, haloalkoxy, alkoxycarbonyl, cycloalkyl, allyl, aryl and heteroaryl; R.sup.3, R.sup.4, R.sup.5 and R.sup.6 are each independently selected from H, alkyl, alkoxy, alkylthio, haloalkyl, haloalkoxy, haloalkylthio, polyalkylenoxy, alkoxycarbonyl, aryl, substituted aryl, heteroaryl and substituted heteroaryl, wherein the alkyl group may be substituted by one or more substituents selected from alkoxy, cycloalkyl, aryl, substituted aryl, heteroaryl and substituted heteroaryl; n, p, q and r are each independently an integer from 0 to 4, wherein when n, p, q and r are two or more, each of the R.sup.3, each of the R.sup.4, each of the R.sup.5 or each of the R.sup.6 may be identical or different; and X.sup.− is a counterion.

2. The compound according to claim 1, wherein Z is selected from C.sub.1-C.sub.12 alkylene, aryl substituted C.sub.1-C.sub.12 alkylene, phenylene, naphthylene, (C.sub.1-C.sub.4 alkylene)-phenylene-(C.sub.1-C.sub.4 alkylene), (C.sub.1-C.sub.4 alkylene)-naphthylene-(C.sub.1-C.sub.4 alkylene), quinoxaline-2,3-diyl, (C.sub.1-C.sub.4 alkylene)-quinoxaline-2,3-diyl-(C.sub.1-C.sub.4 alkylene), phenylene-phenylene, (C.sub.1-C.sub.4 alkylene)-phenylene-phenylene-(C.sub.1-C.sub.4 alkylene) and phenylene-fluorenylene-phenylene, preferably Z is selected from —CH.sub.2—, —(CH.sub.2).sub.2—, —(CH.sub.2).sub.3—, —(CH.sub.2).sub.4—, —(CH.sub.2).sub.5—, —CH.sub.2—CH(CH.sub.3)—CH.sub.2—, —CH.sub.2—CH(CH.sub.2Phenyl)-CH.sub.2—, —(CH.sub.2).sub.2—CH(CH.sub.3)—CH.sub.2—, —(CH.sub.2).sub.3—CH(CH.sub.3)—CH.sub.2—, —(CH.sub.2).sub.2—CH(CH.sub.3)—(CH.sub.2).sub.2—, ##STR00065## ##STR00066##

3. The compound according to claim 1, wherein R.sup.3, R.sup.4, R.sup.5 and R.sup.6 are each independently selected from C.sub.1-C.sub.4 alkyl, C.sub.1-C.sub.4 alkoxycarbonyl, alkanoyl, aroyl, aryl and heteroaryl, wherein the aryl and heteroaryl may be substituted by one or more substituents selected from C.sub.1-C.sub.4 alkyl and C.sub.1-C.sub.4 haloalkyl, preferably, R.sup.3, R.sup.4, R.sup.5 and R.sup.6 are each independently selected from methyl, ethoxycarbonyl, phenyl, p-methylphenyl and p-trifluoromethylphenyl.

4. The compound according to claim 1, wherein the counterion X.sup.− is selected from halide, tetrafluoroborate, tetraphenylborate, hexafluorophosphate, nitrate, methanesulfonate, trifluoromethane sulfonate, toluene sulfonate, hexachloroantimonate, bis(trifluoromethanesulfonyl)imide, perchlorate, acetate and sulfate.

5. The compound according to claim 1, wherein R.sub.a, R.sub.b, R.sub.c, R.sub.d and R.sub.e are each independently selected from H, cyano, halogen, nitro, hydroxyl, alkyl, preferably C.sub.4-C.sub.12 alkyl, haloalkyl, alkoxy, haloalkoxy, alkoxycarbonyl, cycloalkyl, allyl, aryl and heteroaryl.

6. The compound according to claim 1, wherein R.sub.e is H and at least one of R.sub.a, R.sub.b, R.sub.c, and R.sub.d is not H, preferably at least one of R.sub.a and R.sub.b is not H.

7. The compound according to claim 1, wherein said compound is selected from: ##STR00067## ##STR00068## ##STR00069##

8. An electrochromic composition comprising at least one compound as defined in claim 1.

9. The electrochromic composition according to claim 8, wherein said composition comprises a fluid, mesomorphous or gel host medium.

10. The electrochromic composition according to claim 9, wherein the fluid or mesomorphous host medium is selected from the group consisting of organic solvents, liquid crystals, polymers, liquid crystal polymers and mixtures thereof.

11. An electrochromic device comprising a compound according to claim 1.

12. The electrochromic device according to claim 11, wherein said device comprises a mechanism for holding the said compound or said composition in a mechanically stable environment.

13. The electrochromic device according to claim 12, wherein said device comprises a pair of opposed substrates having a gap there between for receiving said compound or said composition, and a frame for holding said pair of substrates adjacent one another.

14. The electrochromic device according to claim 13, wherein said device comprises an optical component provided with at least one transparent cell arrangement juxtaposed in a parallel direction to the surface thereof, each cell being tightly closed and containing said compound or said composition.

15. The electrochromic device according to claim 11, wherein said electrochromic device is an optical article.

16. The electrochromic device according to claim 15, wherein the optical article is an optical lens or an optical filter, a window, a visor, a mirror or a display.

17. The electrochromic device according to claim 16, wherein the window is an aircraft window.

18. The electrochromic device according to claim 16, wherein the optical article is an optical lens.

19. The electrochromic device according to claim 16, wherein the opticle article is an ophthalmic lens.

20. A method for preparing the compound of formula (Ia) ##STR00070## wherein Z, R.sup.3, R.sup.4, R.sup.5, R.sup.6, n, p, q, r and X.sup.− are as defined in formula (I) and R.sup.1 and R.sup.2 are independently selected from optionally substituted phenyl groups of formula (II) wherein R.sub.a, R.sub.b, R.sub.c, R.sub.d and R.sub.e are each independently selected from: H, halogen, cyano, nitro, alkyl, haloalkyl, haloalkoxy, (haloalkoxy)alkyl, arylalkyl, cycloalkyl, (cycloalkyl)alkyl and (heterocycloalkyl)alkyl, alkenyl, alkynyl, allyl, vinyl, aryl, substituted aryl, heteroaryl, substituted heteroaryl, —N(aryl).sub.2, —N(aryl)CO(aryl), —CO-aryl and —CO-substituted aryl; —OR.sup.9, —SR.sup.9, —S(O)R.sup.9, —S(O.sub.2)R.sup.9, —S(O.sub.2)NR.sup.9R.sup.10, —NR.sup.9R.sup.10, —NR.sup.9COR.sup.10, —NR.sup.9CO(aryl), —NR.sup.9aryl, —CH.sub.2OR.sup.9, —CH.sub.2SR.sup.9, —CH.sub.2R.sup.9, —CO—R.sup.9 and —CO.sub.2R.sup.10 wherein R.sup.9 and R.sup.10 are independently selected from H, alkyl, haloalkyl, arylalkyl, cycloalkyl, cycloalkylalkyl and heterocycloalkylalkyl; —S(O.sub.2)NR.sup.11R.sup.12 and —NR.sup.11R.sup.12, wherein R.sup.11 and R.sup.12 form together with the nitrogen atom to which they are linked a saturated 5 to 7 membered heterocycloalkyl which may comprising in addition to the nitrogen atom one further heteroatom selected from oxygen, nitrogen and sulfur, and which may be optionally substituted by one or two groups, identical or different, selected from halogen, —R.sup.9, —OR.sup.9, and —NR.sup.9R.sup.10, wherein R.sup.9 and R.sup.10 are as defined above; —V—W—R.sup.13 wherein: V is selected from oxygen, —N(R.sup.9)—, sulfur, —S(O)— and —S(O.sub.2)— wherein R.sup.9 is as defined above; W is alkylene, which may be substituted by a group selected from halogen and alkoxy; and R.sup.13 is selected from —OR.sup.9, —NR.sup.9(alkyl) and —SR.sup.9 wherein R.sup.9 is as defined above; and OC(O)—R.sup.14 wherein R.sup.14 is selected from alkyl, haloalkyl, alkenyl, —W—R.sup.13, and aryl group which may be substituted by 1 to 4 groups selected from halogen, —R.sup.9, —OR.sup.9, —SR.sup.9, —NR.sup.9R.sup.10, —NR.sub.11R.sup.12, —CO—R.sup.9, —CO.sub.2R.sup.9 wherein R.sup.9, R.sup.10, R.sup.11, R.sup.12, R.sup.13 and W are as defined above; comprising: the step (i) of alkylation of two bipyridinium salts (1) or (1′), with a bifunctional alkylating agent ZL.sub.2 in which the leaving group is selected from sulfonate and carboxylate; and the step (ii) of an anion exchange with an aqueous solution of the desired counterion X.sup.− ##STR00071##

21. An electrochromic device comprising a composition according to claim 8.

Description

EXAMPLES

(1) This invention will be further illustrated by the following non-limiting examples which are given for illustrative purposes only and should not restrict the scope of the appended claims.

Example 1

Synthesis of Compound 2-1: 1′,1′″-[Naphthalene-1,8-diyl-bis(methylene)]-bis{1-(2-isopropylphenyl)-[4,4′-bipyridine]-1,1′-diium}tetrakis(tetrafluoroborate)

(2) A mixture of 1-(2,4-dinitrophenyl)-4,4′-bipyridinium chloride (15 g, 41.8 mmol) and 2-isopropylaniline (16.95 g, 125.5 mmol) in water (300 mL) was refluxed for 4 h, then cooled, filtered and the filtrate washed with CHCl.sub.3 three times. The CHCl.sub.3 extracts were discarded and the water was removed under reduced pressure. The residue was washed with acetone to give 1-(2-isopropylphenyl)-4,4′-bipyridinium chloride (9.17 g, 91%) as a yellow powder.

(3) A solution of 1-(2-isopropylphenyl)-4,4′-bipyridinium chloride (5 g, 20.8 mmol) in water (40 mL) was added dropwise to NaBF.sub.4 (6.8 g, 62 mmol) in water (40 mL). After stirring for 0.5 h the precipitate was filtered off and washed with the minimum of water to give 1-(2-Isopropylphenyl)-4,4′-bipyridinium tetrafluoroborate (5.25 g, 86%) as a pale yellow powder.

(4) A mixture of 1,8-bis(bromomethyl)naphthalene (0.75 g, 2.4 mmol) and 1-(2-isopropylphenyl)-4,4′-bipyridinium tetrafluoroborate (2.59 g, 7.1 mmol) in MeCN (30 mL) was refluxed for 6 h. The mixture was cooled, filtered, washed with MeCN (3×10 mL) and air dried to give 1′,1′″-[naphthalene-1,8-diyl-bis(methylene)]-bis{1-(2-isopropylphenyl)-[4,4′-bipyridine]-1,1′-diium}dibromide bis(tetrafluoroborate) (1.58 g, 64%) as brown needles.

(5) 1′,1′″-[Naphthalene-1,8-diyl-bis(methylene)]-bis{1-(2-isopropylphenyl)-[4,4′-bipyridine]-1,1′-diium}dibromide bis(tetrafluoroborate) (1 g, 1 mmol) in hot water (15 mL) was added to NaBF.sub.4 (1.06 g, 9.6 mmol) in water (30 mL). After stirring for 30 minutes the precipitate was filtered and washed with water to give, after drying, compound 2-1 (0.89 g, 88%) as a pale yellow powder.

(6) δ.sub.H(400 MHz, CD.sub.3OD-D.sub.2O) 9.30 (4H, d, J=6.8 Hz), 9.19 (4H, d, J=6.8 Hz), 8.83 (4H, d, J=6.8 Hz), 8.79 (4H, d, J=6.8 Hz), 7.90-7.50 (10H, m), 7.26 (2H, d, J=7.2 Hz), 6.69 (4H, s), 2.58 (2H, sept, J=6.8 Hz), 1.27 (12H, d, J=6.8 Hz).

Example 2

Synthesis of Compound 2-2: 1′,1′″-{[1,1′-Biphenyl]-2,2′-diylbis(methylene)}bis(1-(2-isopropylphenyl)-[4,4′-bipyridine]-1,1′-diium) tetrakis(tetrafluoroborate)

(7) A solution of 1-(2-isopropylphenyl)-4,4′-bipyridinium tetrafluoroborate (3.19 g, 2.9 mmol), obtained according to example 1, and 2,2′-bis(bromomethyl)-1,1′-biphenyl (1 g, 2.9 mmol) in MeCN (40 mL) was refluxed for 60 h, cooled, filtered, washed with Et.sub.2O (2×50 mL) and air dried. The resulting powder was dissolved in MeOH (20 mL) and added dropwise to a solution of NaBF.sub.4 (3.88 g, 35 mmol) in water (50 mL) with stirring. The solvent was reduced and decanted. The residue was dissolved in hot water (30 mL), cooled, decanted and dried under vacuum to give the compound 2-2 (1.61 g, 51%) as a yellow powder.

(8) δ.sub.H(400 MHz, D.sub.2O) 9.15 (4H, d, J=6.8 Hz), 8.54 (4H, d, J=6.8 Hz), 8.49 (4H, d, J=6.8 Hz), 8.30 (4H, d, J=6.8 Hz), 7.76 (2H, d, J=7.6 Hz), 7.64 (4H, bs), 7.57 (2H, t, J=7.6 Hz), 7.41 (4H, bs), 7.28 (2H, t, J=7.2 Hz), 6.70 (2H, J=7.6 Hz), 5.82 (2H, d, J=15 Hz), 5.61 (2H, d, J=15 Hz), 2.41 (2H, sept, J=6.8 Hz), 1.09 (12H, d, J=6.8 Hz).

Example 3

Synthesis of Compound 1-1: 1,1′″-dihexyl-1,1″-[1,4-phenylenebis(methylene)]bis-4,4′-bipyridinium tetrakis(tetrafluoroborate)

(9) A solution of 4,4′-bipyridine (40 g, 256 mmol) and 1-iodohexane (54.36 g, 256 mmol) in MeCN (200 mL) was heated at reflux. After 16 h the solvent was removed under reduced pressure and the residue dissolved in hot EtOH, cooled to 0° C. for 3 h and then filtered. The filtrate was crystallised from EtOH to give 1,1′-dihexyl-4,4-bipyridinium diiodide (14.6 g, 10%). The solvent was removed under reduced pressure and the residue dissolved in hot DCM and hexane (1 L) was added, the mixture filtered and the process repeated. The resulting precipitate was filtered through silica using MeOH (0-3% in DCM) as eluent. The first band was collected and the solvent removed under reduced pressure to give 1-hexyl-4,4′-bipyridinium iodide (57 g, 60%) as a pale yellow powder.

(10) A solution of 1-hexyl-4,4′-bipyridinium iodide (3.68 g, 10 mmol) and 1,4-di(bromomethyl)benzene (1.06 g, 4 mmol) in MeCN (30 mL) was heated at reflux for 4 h in the dark, cooled, filtered and the residue washed with MeCN to give 1,′1′″-dihexyl-1,1″-[1,4-phenylenebis(methylene)]bis-4,4′-bipyridinium dibromide diiodide (3.89 g, 82%) as an orange powder that was used directed in the next step.

(11) A solution of 1,′1′″-dihexyl-1,1″-[1,4-phenylenebis(methylene)]bis-4,4′-bipyridinium dibromide diiodide (1.5 g, 1.5 mmol) in MeOH (10 mL) was added dropwise to a solution of sodium tetrafluoroborate (1.04 g, 11.9 mmol) in water (20 mL) with stirring. The resulting mixture was stirred at room temperature for 10 min, filtered and the residue washed with water (10 mL) to give compound 1-1 (0.43 g, 31%) as a yellow powder.

(12) δ.sub.H(400 MHz, DMSO-d.sub.6) 9.47 (2H, d, J=6.8 Hz), 9.36 (2H, d, J=6.8 Hz), 8.77 (2H, d, J=6.8 Hz), 8.72 (2H, d, J=6.8 Hz), 7.70 (4H, s), 5.95 (4H, s), 4.69 (4H, t, J=7.6 Hz), 1.98 (4H, br.t), 1.32 (12H, br.s), 0.88 (6H, t, J=6.8 Hz).

(13) Compounds 1-2 and 1-3 can be obtained by an analogous procedure using respectively 1,3-di(bromomethyl)- and 1,2-di(bromomethyl)-benzenes.

Example 4

Synthesis of Compound 2-3: 1′,1′″-(Propane-1,3-diyl)bis{1-(2-isopropylphenyl)-[4,4′-bipyridine]-1,1′-diium}tetrakis(tetrafluoroborate)

(14) A mixture of 1,3-diiodopropane (0.82 g, 2.8 mmol) and 1-(2-isopropylphenyl)-4,4′-bipyridinium tetrafluoroborate (2.5 g, 6.9 mmol) was refluxed in MeCN (30 mL). After 3 days the mixture was cooled, filtered and the residue washed with MeCN to give 1′,1′″-(propane-1,3-diyl)bis{1-(2-isopropylphenyl)-[4,4′-bipyridine]-1,1′-diium}bis(tetrafluoroborate) diiodide (1.93 g, 68%) as a red powder.

(15) 1′,1′″-(Propane-1,3-diyl)bis{1-(2-isopropylphenyl)-[4,4′-bipyridine]-1,1′-diium}bis(tetrafluoroborate) diiodide (1 g, 0.98 mmol) in water-MeOH (20 mL, 1:1) was added dropwise to a solution of NaBF.sub.4 (0.94 g, 8.5 mmol) in water (50 mL) to give in the same manner described for Example 1, compound 2-3 (0.77 g, 84%) as an orange powder.

(16) δ.sub.H(300 MHz, DMSO-d.sub.6) 9.63 (4H, d, J=6.9 Hz), 9.42 (4H, d, J=6.9 Hz), 9.00-8.90 (8H, m), 7.80-7.50 (8H, m), 8.7.90-7.60 (8H, m), 4.87 (4H, t, J=7.2 Hz), 2.83 (2H, quin, J=7.2 Hz), 2.46 (2H, sept, J=6.6 Hz), 1.21 (12H, d, J=6.6 Hz).

Example 5

Synthesis of Compound 2-4: 1′,1′″-(Propane-1,3-diyl)bis{1-(2-(trifluoromethoxy)phenyl)-[4,4′-bipyridine]-1,1′-diium}tetrakis(tetrafluoroborate)

(17) A solution of 1-(2-(trifluoromethoxy)phenyl)-4,4′-bipyridinium tetrafluoroborate (5.13 g, 12.7 mmol) and 1,3-diiodopropane (1.48 g, 5 mmol) in MeCN (40 mL) was heated at reflux for 24 h then cooled and diluted with Et.sub.2O (30 mL). The mixture was stirred for 5 min then left to stand for 0.5 h and filtered. The residue was crystallised from MeOH at 4° C. to give the mixed salt (2.18 g). This material was dissolved in MeOH—H.sub.2O (10 ml, 1:1) and added dropwise to a solution of NaBF.sub.4 (4.34 g, 39 mmol) in H.sub.2O (30 mL) with stirring. Stirring was continued for 0.5 h. The mixture was filtered, washed with water (2×5 mL) and air dried to give compound 2-4 (1.51 g, 29%) as a yellow powder.

(18) δ.sub.H (300 MHz, DMSO-d.sub.6) 9.31 (4H, d, J=7.0 Hz), 9.20 (4H, d, J=7.0 Hz), 8.72 (4H, d, J=7.0 Hz), 8.64 (4H, d, J=7.0 Hz), 7.90-7.60 (8H, m), 4.958 (4H, t, J=7.8 Hz), 2.92 (2H, quin, J=7.8 Hz).

(19) δ.sub.F (282 MHz, CD.sub.3OD-D.sub.2O) −59.10-−59.26 (bs), −152.40-−151.60 (bs).

Example 6

Synthesis of Compound 2-5: 1′,1′″-(Propane-1,3-diyl)bis{1-(4-(trifluoromethoxy)phenyl)-[4,4′-bipyridine]-1,1′-diium}tetrakis(tetrafluoroborate)

(20) A mixture of 1,3-diiodopropane (1.12 g, 3.8 mmol) and 1-[4-(trifluoromethoxy)phenyl]-4,4′-bipyridinium tetrafluoroborate (3.68 g, 9.1 mmol) in MeCN (20 mL) was heated under reflux. After 16 h the mixture was cooled, filtered and the residue air dried to give 1′,1′″-(propane-1,3-diyl)bis{1-(4-(trifluoromethoxy)phenyl)-[4,4′-bipyridine]-1,1′-diium}diiodide bis(tetrafluoroborate) (0.89 g, 20%) as deep red needles.

(21) A solution of 1′,1′″-(propane-1,3-diyl)bis(1-(4-(trifluoromethoxy)phenyl)-[4,4′-bipyridine]-1,1′-diium) diiodide bis(tetrafluoroborate) (0.89 g, 0.75 mmol) in MeOH—H.sub.2O (10 mL, 1:1) and added dropwise to a solution of NaBF.sub.4 (1.64 g, 14.9 mmol) in H.sub.2O (20 mL) with stirring. Stirring was continued for 0.5 h, the mixture filtered. The residue was dissolved in water-MeOH and the solvent was reduced in volume. The resulting precipitate was filtered, washed with cold MeOH (2 mL) and air dried to give 1′,1′″-(propane-1,3-diyl)bis{1-(4-(trifluoromethoxy)phenyl)-[4,4′-bipyridine]-1,1′-diium}tetrakis (tetrafluoroborate) (0.32 g, 41%) as an orange powder.

(22) δ.sub.H (400 MHz, CD.sub.3OD-D.sub.2O) 9.45 (4H, d, J=7.1 Hz), 9.30 (4H, d, J=7.1 Hz), 8.80 (4H, d, J=7.1 Hz), 8.75 (4H, d, J=7.1 Hz), 8.03 (4H, d, J=8.4 Hz), 7.75 (4H, d, J=8.4 Hz), 5.03 (4H, t, J=7.8 Hz), 2.98 (2H, quin, J=7.8 Hz).

(23) δ.sub.F (376 MHz, CD.sub.3OD-D.sub.2O) −58.77 (s), −151.60-−151.80 (bs).

Example 7

Synthesis of Compound 2-6: 1′,1′″-(2-Benzylpropane-1,3-diyl)bis(1-(2-isopropylphenyl)-[4,4′-bipyridine]-1,1′-diium) tetrakis(tetrafluoroborate)

(24) Bromine (11.26 g, 70 mmol) was added dropwise to a suspension of NaBH.sub.4 (6.08 g, 160 mmol) in 1,2-dimethoxyethane (70 mL) under N.sub.2 with stirring at −20° C. After the addition the mixture was stirred at 0° C. for 2 h, cooled to −5° C. and diethyl 2-benzylmalonate (8 g, 32 mmol) was added. The mixture was allowed to warm to room temperature overnight, cautiously poured onto HCl (1 M, 100 mL) and EtOAc (100 mL) with rapid stirring at 5° C. The aqueous phase was separated and extracted with EtOAc (100 mL). The combined organic phases were washed with Na.sub.2CO.sub.3 (2×100 mL), water (100 mL), dried (Na.sub.2SO.sub.4) and the solvent removed under reduced pressure. The residue was filtered through silica using EtOAc (40-100% in hexanes) as eluent. The third band (R.sub.f=0.05; 40% EtOAc in hexanes) was collected and the solvent removed under reduced pressure to give 2-Benzylpropane-1,3-diol (2.87 g, 54%) as a colourless oil which solidified on standing.

(25) δ.sub.H (400 MHz, CDCl.sub.3) 7.10-7.4 (5H, m), 3.83 (2H, dd, J=4, 11 Hz), 3.69 (2H, dd, J=7, 11 Hz), 2.64 (2H, d, J=7 Hz), 2.35 (2H, bs), 2.02-2.16 (1H, m).

(26) δ.sub.C (100 MHz, CDCl.sub.3) 139.85, 129.01, 128.48, 126.17, 65.64, 43.84.

(27) Pyridine (1.57 g, 19.8 mmol) was added dropwise to a solution of triflic anhydride (5.60 g, 19.8 mmol) and 2-benzylpropane-1,3-diol (1.5 g, 9 mmol) in DCM (50 mL) at 0° C. with stirring. Stirring was continued for 1 h and the resulting mixture poured into water (100 mL), separated and the aqueous phase extracted with DCM (2×50 mL). The combined organic phases were dried (Na.sub.2SO.sub.4) and the solvent removed under reduced pressure. The residue was filtered through a short plug of silica using DCM as eluent and the solvent removed under reduced pressure to give the 2-Benzylpropane-1,3-diyl bis(trifluoromethanesulfonate) (3.35 g, 86%) as a colourless oil.

(28) δ.sub.H (400 MHz, CDCl.sub.3) 7.10-7.50 (5H, m), 4.60 (2H, dd, J=4, 11 Hz), 4.50 (2H, dd, J=7, 11 Hz), 2.82 (2H, d, J=7 Hz), 2.55-2.70 (1H, m).

(29) δ.sub.F (376 MHz, CDCl.sub.3) −74.25.

(30) A solution of N-(2-isopropylphenyl)-4-(4-pyridyl)pyridinium tetrafluoroborate (2.79 g, 7.7 mmol) and 2-benzylpropane-1,3-diyl bis(trifluoromethanesulfonate) (1.50 g, 3.5 mmol) in MeCN (40 mL) was heated at reflux for 24 h, cooled and the solvent removed under reduced pressure. The residue was crystallised from hot EtOH, filtered, washed with EtOH and air dried to give the 1′,1′″-(2-Benzylpropane-1,3-diyl)bis(1-(2-isopropylphenyl)-[4,4′-bipyridine]-1,1′-diium) bis(triflate) bis(tetrafluoroborate) (2.20 g, 55%) as a colourless powder.

(31) δ.sub.H (400 MHz, CD.sub.3OD-D.sub.2O) 9.30 (4H, d, J=7.2 Hz), 9.23 (4H, d, J=7.2 Hz), 8.74 (4H, d, J=7.2 Hz), 8.60 (4H, d, J=7.2 Hz), 7.74-8.87 (4H, m), 7.54-7.66 (4H, m) 7.15 (5H, br.s), 4.90-5.22 (4H, m), 3.67-3.80 (1H, m), 3.09 (2H, d, J=7.2 Hz), 2.52-2.66 (2H, m), 1.28 (12H, d, J=7.2 Hz).

(32) δ.sub.F (376 MHz, CD.sub.3OD-D.sub.2O) −79.65 (br.s) and −151.81-−151.92 (br.s).

(33) A solution of 1′,1′″-(2-benzylpropane-1,3-diyl)bis(1-(2-isopropylphenyl)-[4,4′-bipyridine]-1,1′-diium) bis(triflate) bis(tetrafluoroborate) (1.5 g, 1.3 mmol) in water-MeOH (10 mL, 1:1) was added dropwise to a solution of NaBF.sub.4 (1.43 g, 13 mmol) in water (30 mL) with stirring. The mixture was heated to dissolution, cooled with rapid stirring, filtered and the residue crystallised from hot water, filtered, washed with water (2×5 mL) and air dried. The residue was again added to NaBF.sub.4 (1.43 g, 13 mmol) in water (30 mL) and heated to dissolution, cooled, filtered, crystallised from hot water, filtered and air dried to give compound 2-6 (1.01 g, 75%) as a cream powder.

(34) δ.sub.H (400 MHz, CD.sub.3OD-D.sub.2O) 9.27 (4H, d, J=7.2 Hz), 9.20 (4H, d, J=7.2 Hz), 8.72 (4H, d, J=7.2 Hz), 8.57 (4H, d, J=7.2 Hz), 7.75-7.83 (4H, m), 7.55-7.63 (4H, m) 7.130 (5H, br.s), 4.94-5.19 (4H, m), 3.63-3.81 (1H, m), 3.08 (2H, d, J=7.2 Hz), 2.49-2.66 (2H, m), 1.26 (12H, d, J=7.2 Hz).

(35) δ.sub.F (376 MHz, CD.sub.3OD-D.sub.2O) −152.36-−152.46 (br.s).

Example 8

Synthesis of Compound 2-7: 1′,1′″-[1,2-Phenylenebis(methylene)]bis{1-(2-isopropylphenyl)-[4,4′-bipyridine]-1,1′-diium}tetrakis(tetrafluoroborate)

(36) A solution of 1-(2-isopropylphenyl)-4,4′-bipyridinium tetrafluoroborate (3.43 g, 9.5 mmol) and 1,2-bis(bromomethyl)benzene (1.00 g, 3.8 mmol) in MeCN (40 mL) was heated at reflux for 16 h. After cooling the mixture was filtered, washed with MeCN (2×5 mL) and air dried. The resulting hygroscopic yellow solid was dissolved in water (20 mL) and added dropwise to a solution of NaBF.sub.4 (2.50 g, 22.7 mmol) in water (30 mL) with stirring. The resulting mixture was heated to dissolution, cooled to room temperature with rapid stirring, filtered, washed with water (2×5 mL) and air dried to give compound 2-7 (1.40 g, 37%) as a colourless powder.

(37) δ.sub.H (400 MHz, CD.sub.3OD-D.sub.2O), 9.27 (4H, d, J=6.5 Hz), 9.20 (4H, d, J=6.5 Hz), 8.80 (4H, d, J=6.5 Hz), 8.76 (4H, d, J=6.5 Hz), 7.790 (4H, br.s), 7.65-7.75 (2H, m), 7.58 (4H, br.s), 7.40-7.50 (2H, m), 6.20 (4H, s), 2.57 (2H, m) and 1.25 (12H, d, J=6.8 Hz)

(38) δ.sub.F, (376 MHz, CD.sub.3OD-D.sub.2O), −151.12-−151.27 (br.s)

Example 9

Synthesis of Compound 2-8: 1′,1′″-[1,2-Phenylenebis(methylene)]bis{1-(2-(trifluoromethoxy)phenyl)-[4,4′-bipyridine]-1,1′-diium}tetrakis(tetrafluoroborate)

(39) A solution of 1-[2-(trifluoromethoxy)phenyl]-4,4′-bipyridinium tetrafluoroborate (3.83 g, 9.5 mmol) and 1,2-bis(bromomethyl)benzene (1.00 g, 3.8 mmol) in MeCN (40 mL) was heated at reflux for 16 h. After cooling, the mixture was filtered, washed with MeCN (2×5 mL) and air dried. The resulting yellow solid was dissolved in water (20 mL) and added dropwise to a solution of NaBF.sub.4 (2.50 g, 22.7 mmol) in water (30 mL) with stirring. Stirring was continued for 0.5 h and the resulting precipitate filtered, washed with water (2×5 mL) and air dried to give compound 2-8 (1.73 g, 43%) as a colourless powder.

(40) δ.sub.H (400 MHz, CD.sub.3OD-D.sub.2O), 9.43 (4H, d, J=6.8 Hz), 9.23 (4H, d, J=6.8 Hz), 8.88 (4H, d, J=6.8 Hz), 8.79 (4H, d, J=6.8 Hz), 7.93-8.01 (4H, m), 7.82-7.88 (4H, t, J=7.6 Hz), 7.67-7.74 (2H, m), 7.40-7.48 (2H, m) and 6.23 (4H, s)

(41) δ.sub.F, (376 MHz, CD.sub.3OD-D.sub.2O), −58.98 (s), 151.87-−151.97 (br.s)

Example 10

Synthesis of Compound 1-4a: 1,3-Bis(1′-hexyl-4,4′-bipyridinium-1-yl)propane tetrakis(tetrafluoroborate)

(42) A solution of 1-hexyl-4,4′-bipyridinium iodide (1.68 g, 4.6 mmol) and 1,3-diiodopropane (0.60 g, 0.45 mmol) in MeCN (50 mL) was heated at reflux for 4 days. The mixture was cooled, then filtered and the residue washed with DCM to give 1,3-Bis(1′-hexyl-4,4′-bipyridinium-1-yl)propane tetraiodide (1.29 g, 62%) as an orange powder.

(43) A solution of 1,3-bis(1′-hexylbipyridinium-1-yl)propane tetraiodide (1.00 g, 0.97 mmol) in H.sub.2O (50 mL) was added dropwise to a solution of sodium tetrafluoroborate (1.28 g, 11.6 mmol) in water (20 mL). The resulting mixture was stirred at room temperature for 10 min, filtered and washed with water (20 mL) to give compound 1-4a (0.21 g, 25%) as an orange powder.

(44) δ.sub.H (400 MHz, DMSO-d.sub.6,) 9.50-9.30 (8H, m), 8.85 (4H, d, J=6.8 Hz), 8.79 (4H, d, J=6.8 Hz), 4.82 (4H, t, J=7.2 Hz), 4.70 (4H, t, J=7.2 Hz), 2.90-2.70 (2H, m), 2.10-1.90 (4H, m), 1.40-1.20 (12H, m), 0.88 (6H, t, J=6.8 Hz).

(45) Compound 1-4b can be obtained through an identical procedure by substituting the counterion with ClO.sub.4.sup.−.

Example 11

Synthesis of Compound 1-5: 1,4-Bis(1′-hexyl-4,4′-bipyridinium-1-yl)butane tetrakis(tetrafluoroborate)

(46) A solution of 1-hexylbipyridinium iodide (3.68 g, 10 mmol) and 1,4-diiodobutane (1.24 g, 4 mmol) in MeCN (80 mL) was heated at reflux for 2 weeks. The mixture was cooled, then filtered and the residue washed with MeCN to give 1,4-Bis(1′-hexyl-4,4′-bipyridinium-1-yl)butane tetraiodide (3.32 g, 79%) as an orange powder.

(47) A solution of 1,4-bis(1′-hexyl-4,4′-bipyridinium-1-yl)butane tetraiodide (3 g, 2.9 mmol) in warm (50° C.) H.sub.2O (10 mL) was added dropwise to a solution of sodium tetrafluoroborate (2.52 g, 23 mmol) in water (10 mL) at 0° C. with stirring. The resulting mixture was stirred at room temperature for 10 min. Water (150 mL) was added and heating was continued until dissolution was complete. The solution was cooled to 0° C., filtered, washed with water (2×10 mL) and filtered to give compound 1-5 (2.54 g, 63%) as an orange powder.

(48) δ.sub.H (400 MHz, DMSO-d.sub.6,) 9.50-9.20 (8H, m), 8.90-8.70 (8H, m), 4.77 (4H, br.s), 4.70 (4H, t, J=7.6 Hz), 2.10 (4H, br.s), 1.99 (4H, br.s), 1.33 (12H, br.s), 1.00-0.80 (6H, m).

Example 12

Synthesis of Compound 2-9: 1′,1′″-[1,2-Phenylenebis(methylene)]bis{1-(2-cyanophenyl)-[4,4′-bipyridine]-1,1′-diium}tetrakis(tetrafluoroborate)

(49) A solution of 1-(2-cyanophenyl)-4,4′-bipyridinium tetrafluoroborate (2 g, 5.8 mmol) and 1,2-bis(bromomethyl)benzene (0.61 g, 2.3 mmol) in MeCN (40 mL) was heated at reflux for 16 h, cooled and filtered. The product was washed with MeCN (2×5 mL) and air dried. The resulting solid and NaBF.sub.4 (2.64 g, 30 mmol) were heated in water (100 mL) and MeOH (100 mL) until dissolution, filtered through celite, cooled and the solvent reduced. The resulting precipitate was filtered, washed with water (2×30 mL) and air dried to give Compound 2-9 (1.41 g, 63%) as a cream powder.

(50) δ.sub.H (400 MHz, DMSO-d.sub.6) 9.83 (4H, d, J=6.5 Hz), 9.47 (4H, d, J=6.5 Hz), 9.11 (4H, d, J=6.5 Hz), 9.00 (4H, d, J=6.5 Hz), 8.38 (2H, d, J=7.6 Hz), 8.10-8.25 (4H, m), 8.03 (2H, t, J=7.2 Hz), 7.50-7.65 (2H, m), 7.25-7.35 (2H, m), 6.24 (s, 4H).

(51) δ.sub.F (376 MHz, DMSO-d.sub.6) −148.0-−148.2 (br.s).

Example 13

Synthesis of Compound 2-10: 1′,1′″-[Quinoxaline-2,3-diylbis(methylene)]bis{1-(2-cyanophenyl)-[4,4′-bipyridine]-1,1′-diium}tetrakis(tetrafluoroborate)

(52) A solution of 1-(2-cyanophenyl)-4,4′-bipyridinium tetrafluoroborate (2.73 g, 7.9 mmol) and 2,3-bis(bromomethyl)quinoxaline (1.00 g, 3.2 mmol) in MeCN (40 mL) was heated at reflux for 16 h, and cooled. The product was filtered, washed with MeCN (2×5 mL) and air dried. The green solid in hot water (40 mL) and MeOH (40 mL) was added dropwise to NaBF.sub.4 (4.18 g, 38 mmol) in water (40 mL) with stirring. The mixture was heated to dissolution, filtered through celite, cooled, then filtered, washed with water (2×10 mL) and air dried. The residue was crystallised from hot water-MeOH, filtered washed with MeOH (5 mL) and air dried to give Compound 2-10 (1.47 g, 48%) as a pale yellow powder.

(53) δ.sub.H (400 MHz, DMSO-d.sub.6) 9.60 (4H, d, J=6.8 Hz), 9.44 (4H, d, J=6.8 Hz), 9.01 (4H, d, J=6.8 Hz), 8.93 (4H, d, J=6.5 Hz), 8.26 (2H, d, J=7.5 Hz), 8.00-8.20 (6H, m), 7.80-7.95 (4H, m) and 6.72 (4H, m).

(54) δ.sub.F (376 MHz, DMSO-d.sub.6) −151.1-−151.2 (br.s).

Example 14

Synthesis of Compound 2-11: 1′,1′″-[Quinoxaline-2,3-diylbis(methylene)]bis{1-(2-(trifluoromethoxy)phenyl)-[4,4′-bipyridine]-1,1′-diium}tetrakis(tetrafluoroborate)

(55) A solution of 1-(2-trifluoromethoxyphenyl)-4,4′-bipyridinium tetrafluoroborate (3.07 g, 7.9 mmol) and 2,3-bis(bromomethyl)quinoxaline (1.00 g, 3.2 mmol) in MeCN (40 mL) was heated at reflux for 16 h then cooled. The product was filtered, washed with MeCN (2×5 mL) and air dried. The green solid in hot water (30 mL) and MeOH (20 mL) was added dropwise to NaBF.sub.4 (4.18 g, 38 mmol) in water (30 mL) with stirring. Stirring was continued for 0.5 h and the resulting precipitate filtered and washed with water (2×10 mL). The residue was crystallised from hot water-MeOH, filtered and washed with MeOH (5 mL) and air dried to give Compound 2-11 (2.25 g, 67%) as lime green plates.

(56) δ.sub.H (400 MHz, DMSO-d.sub.6) 9.81 (4H, d, J=6.5 Hz), 9.50 (4H, d, J=6.5 Hz), 9.15 (4H, d, J=6.5 Hz), 9.11 (4H, d, J=6.5 Hz), 8.13 (2H, d, J=7.7 Hz), 7.80-8.05 (10H, m) and 6.65 (4H, s).

(57) δ.sub.F (376 MHz, DMSO-d.sub.6) −57.03 (s) and −148.1_−148.2 (br.s).

Example 15

Synthesis of Compound 2-12: 1′,1′″-[Quinoxaline-2,3-diylbis(methylene)]bis{1-(2-isopropylphenyl)-[4,4′-bipyridine]-1,1′-diium}tetrakis(tetrafluoroborate)

(58) A solution of 1-(2-isopropylphenyl)-4,4′-bipyridinium tetrafluoroborate (2.07 g, 7.9 mmol) and 2,3-bis(bromomethyl)quinoxaline (1.00 g, 3.2 mmol) in MeCN (40 mL) was heated at reflux for 16 h, cooled. The product was filtered, washed with MeCN (2×5 mL) and air dried. The yellow solid and NaBF.sub.4 (4.18 g, 38 mmol) were heated to dissolution in water (20 mL) and MeOH (10 mL), and cooled. The product was filtered, washed with water (2×5 mL), acetone (4 mL) and air dried to give Compound 2-12 (1.28 g, 37%) as a pale yellow powder.

(59) δ.sub.H (400 MHz, DMSO-d.sub.6) 9.69 (4H, d, J=6.5 Hz), 9.49 (4H, d, J=6.5 Hz), 9.00-9.20 (8H, m), 7.70-7.95 (10H, m), 7.55-7.65 (2H, m), 6.51 (4H, s), 2.48 (2H, m) and 1.24 (12H, t, J=7.2 Hz).

(60) δ.sub.F (376 MHz, DMSO-d.sub.6) −148.1-148.2 (br.s).

Example 16

Synthesis of Compound 2-13: 1′,1′″-[Pyridine-2,6-diylbis(methylene)]bis{1-(2-isopropylphenyl)-[4,4′-bipyridine]-1,1′-diium}tetrakis(tetrafluoroborate) 2,6-Bis(bromomethyl)pyridine

(61) Sodium borohydride (5 g, 131 mmol) was added portionwise to a solution of dimethyl pyridine-2,6-dicarboxylate (5.5 g, 28 mmol) in dry EtOH (85 mL) under N.sub.2 at 0° C. with stirring. The resulting mixture was warmed to room temperature and stirred for 3 h and then heated at reflux for 10 h. After this time the mixture was cooled and the solvent removed under reduced pressure. Water (200 mL) was added and the resulting solution extracted with EtOAc (20×50 mL). After drying (Na.sub.2SO.sub.4) the extracts were filtered through silica, using EtOAc as eluent, and the solvent removed under reduced pressure. The residue was triturated with Et.sub.2O and air dried. The resulting colourless powder was dissolved in HBr (48% aqueous, 15 mL) and heated at reflux for 2 h, then cooled and neutralised with conc. aqueous NaOH at 0° C. The product was filtered, washed with water (2×10 mL) and air dried to give 2,6-bis(hydroxymethyl)pyridine (1.39 g, 19%) as a colourless powder.

(62) Compound 2-13

(63) A solution of 2,6-bis(bromomethyl)pyridine (0.70 g, 2.6 mmol) in MeCN (50 mL) was added dropwise to a refluxing solution of 1-(2-isopropylphenyl)-4,4′-bipyridinium tetrafluoroborate (5.74 g, 15.8 mmol) in MeCN (50 mL) over 2 h with stirring under N.sub.2. Heating was continued for 2 h more and then the solution was cooled and slowly diluted with Et.sub.2O with stirring. The resulting precipitate was decanted off to leave a gummy residue. The residue was dissolved in MeCN and acetone was added. The resulting precipitate was filtered, washed with acetone and dried to give a bright yellow hygroscopic solid. The solid was dissolved in water (20 mL) and added dropwise to a solution of NaBF.sub.4 (5.81 g, 52.8 mmol) in water (50 mL) with stirring. The resulting precipitate was heated to dissolution and then the solution was cooled with rapid stirring. The precipitate was filtered off, then dissolved in hot water (10 mL), and again cooled with rapid stirring, the precipitated product was filtered, washed with water (5 mL) and air dried to give compound 2-13 (0.80 g, 30%) as a colourless powder.

(64) δ.sub.H [400 MHz, (CD.sub.3).sub.2CO]: 9.30-9.15 (8H, m), 8.79 (4H, d, J=6.8 Hz), 8.73 (4H, d, J=6.8 Hz), 8.13 (1H, t, J=8.0 Hz), 8.85-8.72 (6H, m), 8.64-8.52 (4H, d, J=8.0 Hz), 6.05 (4H, s), 2.60 (2H, 2×sept., J=6.8 Hz), 1.25 (12H, d, J=6.8 Hz)

(65) δ.sub.F (376 MHz, (CD.sub.3).sub.2CO]: 151.75 (s) and 151.62 (t, J=1 Hz)

(66) δ.sub.13C[100.6 MHz, (CD.sub.3).sub.2CO]: 152.19, 151.27, 150.71, 146.89, 146.46, 142.99, 140.49, 140.10, 132.53, 127.92, 127.69, 127.27, 127.11, 125.50, 124.11, 64.60, 27.74, 22.92.

Example 17

Synthesis of Compound 3-1: 1,1′-Bis-(3-tert-butylphenyl)-4,4′-bipyridinium bis(tetrafluoroborate)

(67) A solution of 1,1′-bis-(2,4-dinitrophenyl)-4,4′-bipyridinium dichloride (3 g, 5.3 mmol) in hot water (50 mL) was added dropwise to a refluxing solution of 3-tert-butylaniline (4.78 g, 32 mmol) in water (50 mL). The resulting mixture was heated at reflux for 2 h, cooled, washed with CHCl.sub.3 (3×50 mL) and the solvent removed under reduced pressure. The residue was dissolved in MeOH and acetone was added. The resulting precipitate was filtered and washed with acetone to give 1,1′-Bis-(3-tert-butylphenyl)-4,4′-bipyridinium dichloride (1.85 g, 70%) as a pale yellow powder that was used directly in the next stage.

(68) A solution of 1,1′-bis-(3-tert-butylphenyl)-4,4′-bipyridinium dichloride (1.5 g, 3 mmol) in hot water-MeOH (20 mL) was added dropwise to a solution of sodium tetrafluoroborate (2.01 g, 18 mmol) in water (20 mL) at room temperature with stirring. The resulting mixture was stirred at room temperature for 10 min and filtered. The product was washed with water (10 mL), air dried and crystallized from hot MeOH. On cooling to 0° C. the precipitated product was filtered off and washed with MeOH to give Compound 3-1 (1.10 g, 61%) as a pale yellow powder.

(69) δ.sub.H (400 MHz, DMSO-d.sub.6) 9.39 (4H, d, J=6.4 Hz), 8.79 (4H, d, J=6.4 Hz), 7.80-7.95 (4H, m), 7.57-7.75 (4H, m) and 1.39 (18H, s).

(70) δ.sub.F (376 MHz, DMSO-d.sub.6) −155.4-−155.8 (bs).

Example 18

Synthesis of Compound 3-2: 1-(2-Trifluoromethoxyphenyl)-1′-(2-isopropylphenyl)-4,4′-bipyridinium bis(tetrafluoroborate)

(71) A solution of 1-(2-isopropylphenyl)-4,4′-bipyridinium tetrafluoroborate (4 g, 11 mmol) and 2,4-dinitrophenyl p-toluenesulfonate (6.94 g, 20.5 mmol) in MeCN (40 mL) was heated at reflux for 2 days. The solvent was reduced, the residue was chilled to 0° C. and the resulting precipitate filtered, washed with cold MeCN (5 mL) and air dried to give 1-(2,4-dinitrophenyl)-1′-(2-isopropylphenyl)-4,4′-bipyridinium ditosylate (3.00 g, 35%). The solvent was removed and the residue dissolved in water —CHCl.sub.3 (200 mL, 1:1), conc. HCl (0.8 mL) was added and the mixture filtered. The residue was dissolved in hot MeOH-water (80 mL, 1:1) and filtered into a solution of NaBF.sub.4 (7.47 g, 68 mmol) in water (100 mL) with rapid stirring. After 0.5 h the resulting precipitate was filtered, washed with water (2×10 mL) and air dried to give 1-(2,4-Dinitrophenyl)-1′-(2-isopropylphenyl)-4,4′-bipyridinium bis(tetrafluoroborate) (2.72 g, 40%) as a pale yellow powder.

(72) A solution of 1-(2,4-dinitrophenyl)-1′-(2-isopropylphenyl)-4,4′-bipyridinium bis(tetrafluoroborate) (1.44 g, 2.3 mmol) and 2-trifluoromethoxyaniline (0.83 g, 4.7 mmol) in MeOH (30 mL) was heated at reflux for 2 days. The mixture was cooled, poured into water (200 mL) and washed with CHCl.sub.3 (3×100 ml) and the solvent removed under reduced pressure. The residue was triturated with EtOH to give Compound 3-2 (1.10 g, 77%) as a pale yellow powder.

(73) δ.sub.H (300 MHz, CD.sub.3OD) 9.56 (2H, d, J=6.9 Hz), 9.42 (2H, d, J=6.9 Hz), 8.96 (2H, d, J=6.9 Hz), 8.91 (2H, d, J=6.9 Hz), 7.91-9.10 (2H, m), 7.73-7.89 (4H, m), 7.52-7.70 (2H, m), 2.64 (1H, m), 1.30 (6H, d, J=6.8 Hz).

(74) δ.sub.F (282 MHz, CD.sub.3OD) −59.49 (s), −154.05-154.15 (br.s).

Example 19

Synthesis of Compound 3-3: 1-(2-Trifluoromethoxyphenyl)-1′-(4-trifluoromethoxyphenyl)-4,4′-bipyridinium bis(tetrafluoroborate)

(75) A solution of 1-(2-trifluoromethoxyphenyl)-4,4′-bipyridinium tetrafluoroborate (2.30 g, 5.7 mmol) and 2,4-dinitrophenyl p-toluenesulfonate (2.87 g, 8.5 mmol) in MeCN (40 mL) was heated at reflux for 16 h. The solvent was removed under reduced pressure and the residue dissolved in water (200 mL), washed with CHCl.sub.3 (3×50 mL). The solvent was removed under reduced pressure, the residue washed with EtOH and air dried to give 1-(2,4-Dinitrophenyl)-1′-(2-trifluoromethoxyphenyl)-4,4′-bipyridinium bis(tetrafluoroborate) (1.42 g, 38%) as a lime-coloured powder.

(76) A solution of 1-(2,4-dinitrophenyl)-1′-(2-trifluoromethoxyphenyl)-4,4′-bipyridinium bis(tetrafluoroborate) (1.42 g, 2.2 mmol) and 4-trifluoromethoxyaniline (1.15 g, 6.5 mmol) in MeOH (20 mL) was heated at reflux for 2 h, cooled and the solvent removed under reduced pressure. The residue was twice triturated with hot EtOH. After cooling the product was filtered and air dried to give Compound 3-3 (1.04 g, 74%) as a cream powder.

(77) δ.sub.H (300 MHz, CD.sub.3OD) 9.45-9.65 (4H, m), 8.80-9.03 (4H, m), 7.66-8.17 (8H, m).

(78) δ.sub.F (282 MHz, CD.sub.3OD) −59.49 (s), −59.52 (s), −154.00-154.10 (br.s).

Example 20

Synthesis of Compound 3-4: 1,1′-Bis-(2-cyanophenyl)-4,4′-bipyridinium bis(tetrafluoroborate)

(79) A solution of 1,1′-bis-(2,4-dinitrophenyl)-4,4′-bipyridinium dichloride (8 g, 14.3 mmol) in hot water (150 mL) was added dropwise to a refluxing solution of 2-aminobenzonitrile (10.1 g, 85.6 mmol) in water (150 mL). The resulting mixture was heated at reflux for 16 h, then cooled. The product was filtered, washed with CHCl.sub.3 (3×100 mL) and the solvent removed under reduced pressure. The residue was washed with acetone to give 1,1′-Bis-(2-cyanophenyl)-4,4′-bipyridinium dichloride (5.96 g, 97%) as a tan powder.

(80) A solution of 1,1′-bis-(2-cyanophenyl)-4,4′-bipyridinium dichloride (2 g, 4.6 mmol) in MeOH (20 mL) was added dropwise to a solution of sodium tetrafluoroborate (3.06 g, 27.8 mmol) in water (150 mL) with stirring. The resulting mixture was stirred at room temperature for 0.5 h, then filtered and washed with water (20 mL). Trituration with hot EtOH gave Compound 3-4 (1.99 g, 80%) as a tan powder.

(81) δ.sub.H (300 MHz, DMSO-d.sub.6) 9.85 (4H, d, J=6.7 Hz), 9.22 (4H, d, J=6.7 Hz), 8.36 (2H, d, J=7.5 Hz), 8.10-8.25 (4H, m), 8.96-8.08 (2H, m).

(82) δ.sub.F (282 MHz, DMSO-d.sub.6) −148.2-−148.4 (br.s).

Example 21

Synthesis of Compound 3-5: 1-(3-Cyanophenyl)-1′-(2-isopropylphenyl)-4,4′-bipyridinium bis(tetrafluoroborate)

(83) A solution of 1-(2,4-dinitrophenyl)-1′-(2-isopropylphenyl)-4,4′-bipyridinium bis(tetrafluoroborate) (1.5 g, 2.4 mmol) and 3-aminobenzonitrile (0.57 g, 4.8 mmol) in MeOH-EtOH (40 mL, 1:1) was heated at reflux for 3 h, cooled and the solvent removed under reduced pressure. The residue was triturated with hot EtOH, cooled and filtered to give Compound 3-5 (1.25 g, 93%) as a pale yellow powder.

(84) δ.sub.H (300 MHz, CD.sub.3OD) 9.52 (2H, d, J=6.9 Hz), 9.33 (2H, d, J=6.9 Hz), 8.84-8.97 (4H, m), 8.36-8.43 (1H, m), 8.17-8.32 (2H, m), 7.98-8.08 (1H, t, J=8 Hz), 7.74-7.84 (2H, m), 7.55-7.67 (2H, m), 2.61 (1H, m), 1.28 (6H, d, J=6.8 Hz).

(85) δ.sub.F (282 MHz, CD.sub.3OD) −152.33-152.45 (br.s).

Example 22

Synthesis of Compound 3-6: 1-(2-tert-Butylphenyl)-1′-phenyl-4,4′-bipyridinium bis(tetrafluoroborate)

(86) A solution of 1-(2,4-dinitrophenyl)-4,4′-bipyridinium chloride (5 g, 13.9 mmol) and 2-tert-butylaniline (6.23 g, 41.9 mmol) in water (150 mL) was heated at reflux for 7 days. After cooling, the mixture was filtered and washed with CHCl.sub.3 (3×100 mL). The solvent was removed under reduced pressure and the residue washed with acetone to give 1-(2-tert-Butylphenyl)-4,4′-bipyridinium chloride (3.14 g, 69%) as a pale yellow powder.

(87) A solution of 1-(2-tert-butylphenyl)-4,4′-bipyridinium chloride (3.1 g, 9.5 mmol) in water (30 mL) was added dropwise to a solution of NaBF.sub.4 (3.15 g, 28.6 mmol) in water (30 mL) with stirring. The mixture was stirred for 0.5 h and filtered. The residue was washed with water (10 mL) and air dried to give 1-(2-tert-Butylphenyl)-4,4′-bipyridinium tetrafluoroborate (3.08 g, 86%) as a colourless powder.

(88) A solution of 1-(2-tert-butylphenyl)-4,4′-bipyridinium tetrafluoroborate (2.61 g, 6.9 mmol) and 2,4-dinitrophenyl p-toluenesulfonate (3.52 g, 10.4 mmol) in MeCN (30 mL) was heated at reflux for 24 h. After cooling the mixture was filtered and washed with MeCN to give 1-(2,4-dinitrophenyl)-1′-(2-tert-butylphenyl)-4,4′-bipyridinium ditosylate (1.97 g, 35%). The solvent was removed under reduced pressure and the residue triturated with MeOH-Et.sub.2O (1:1, 200 mL). After filtration, the solvent was removed under reduced pressure. The residue was subjected to Soxhlet extraction with Et.sub.2O for 2 days. The residue from the extraction thimble was dissolved in hot MeOH-water (100 mL, 4:1) and filtered into a solution of NaBF.sub.4 (17.5 g, 159 mmol) in water (300 mL) with rapid stirring. After 0.5 h the resulting precipitate was filtered, washed with water (2×20 mL). The residue was crystallised from hot MeOH-water (4:1, 100 mL) and air dried to give 1-(2-tert-Butylphenyl)-1′-(2,4-dinitrophenyl)-4,4′-bipyridinium bis(tetrafluoroborate) (2.17 g, 50%) as cream plates.

(89) A solution of 1-(2-tert-butylphenyl)-1′-(2,4-dinitrophenyl)-4,4′-bipyridinium bis(tetrafluoroborate) (1.5 g, 2.4 mmol) and aniline (0.44 g, 4.7 mmol) in MeOH (30 mL) was refluxed for 2 h, cooled and the solvent removed under reduced pressure. The residue was triturated (twice) with hot EtOH (20 mL) and recrystallised (twice) from EtOH containing a few drops of water to give Compound 3-6 (0.56 g, 43%) as colourless prisms.

(90) δ.sub.H (300 MHz, CD.sub.3OD-D.sub.2O) 9.43-9.53 (4H, m), 8.85-8.92 (4H, m), 7.90-7.98 (3H, m), 7.82-7.88 (3H, m), 7.77 (1H, t, J=7.5 Hz), 7.58 (1H, t, J=7.9 Hz), 7.47 (1H, t, J=7.9 Hz) 1.26 (9H, s).

(91) δ.sub.F (282 MHz, CD.sub.3OD-D.sub.2O) −152.34-152.44 (br.s).

Example 23

Synthesis of Compound 3-7: 1,1′-Bis-(2-tert-butylphenyl)-4,4′-bipyridinium bis(tetrafluoroborate)

(92) A solution of 1,1′-bis-(2,4-dinitrophenyl)-4,4′-bipyridinium dichloride (6 g, 10.7 mmol) in hot water (100 mL) was added dropwise to a refluxing solution of 2-tert-butylaniline (9.56 g, 64.2 mmol) in water (100 mL). The resulting mixture was heated at reflux for 20 days, cooled then washed with CHCl.sub.3 (2×50 mL). The solvent was removed under reduced pressure, the residue was dissolved in MeOH and precipitated with EtOAc to give 1,1′-Bis-(2-tert-butylphenyl)-4,4′-bipyridinium dichloride (2.30 g, 44%) as a pale yellow powder.

(93) A solution of 1,1′-bis-(2-tert-butylphenyl)-4,4′-bipyridinium dichloride (1.5 g, 3.2 mmol) in hot water (5 mL) was added dropwise to a solution of sodium tetrafluoroborate (2.11 g, 22.2 mmol) in water (5 mL) at room temperature with stirring. The resulting mixture was stirred for 10 min, filtered and washed with water (5 mL). The residue was crystallised from MeOH to give Compound 3-7 (1.08 g, 59%) as pale yellow microplates.

(94) δ.sub.H (400 MHz, DMSO-d.sub.6) 9.56 (4H, d, J=6.9 Hz), 8.89 (4H, d, J=6.9 Hz), 7.94 (2H, dd, J=1.1, 8.2 Hz), 7.76 (2H, dd, J=1.1, 8.2 Hz), 7.42-7.62 (4H, m), 1.28 (18H, s).

Example 24

Synthesis of Compound 3-8: 1-(2-Cyanophenyl)-1′-(2-isopropylphenyl)-4,4′-bipyridinium bis(tetrafluoroborate)

(95) A solution of 1-(2,4-dinitrophenyl)-1′-(2-isopropylphenyl)-4,4′-bipyridinium bis(tetrafluoroborate) (1.5 g, 2.4 mmol) and 2-aminobenzonitrile (5.7 g, 48 mmol) in isopropanol (40 mL) was heated at reflux for 2 days. After cooling the solvent removed under reduced pressure. The residue was triturated with hot EtOH, cooled and filtered to give Compound 3-8 (1.08 g, 81%) as a colourless powder.

(96) δ.sub.H (300 MHz, CD.sub.3OD) 9.577 (2H, d, J=6.9 Hz), 9.33 (2H, d, J=6.9 Hz), 9.00 (2H, d, J=6.9 Hz), 8.91 (2H, d, J=6.9 Hz), 8.00-8.30 (4H, m), 7.72-7.88 (2H, m), 7.54-7.67 (2H, m), 2.61 (1H, m), 1.28 (6H, d, J=6.8 Hz).

(97) δ.sub.F (282 MHz, CD.sub.3OD) −152.79-152.90 (br.s).

Example 25

Evaluation of Oxido-Reduction Potential and of the Absorption Spectrum of the Compounds of the Invention

(98) The oxido-reduction potentials of the compounds are measure by a method of cyclic voltammetry with 3 electrodes.

(99) The 3 electrodes used are: 1 Platinum working electrode 1 Platinum auxiliary or counter electrode 1 Platinum reference electrode which is immersed into a solution consisting of 0.01M AgNO.sub.3+0.1M TBAP (tetrabutylamonium perchlorate) in acetonitrile.

(100) The potential values indicated are the first reduction potential for the compounds, with regards to the standard hydrogen reference electrode (SHE).

(101) The analyzed solution comprises 0.01M of the compound to be analyzed and 1M of TBAP salt.

(102) The scan rate of the potential is fixed to 100 mV/s.

(103) The absorption spectra of the compounds are measured with a solution comprising 0.01M of the compound to be analyzed, 0.02M Phenothiazine (Phtz) or 10-Methylphenothiazine (Mephtz) and 1M of TBAP salt in propylene carbonate as solvent.

(104) This solution is introduced into a quartz tank where at least one glass electrode coated with Indium Tin Oxide (ITO) is placed in order to colour the analyzed compound on this electrode. The absorption spectrum of the compound in the time domain is measured by a spectrophotometer.

(105) The reducing agent (phenothiazine for all compounds except compounds 1-3, 2-1, 2-2, 2-5 to 2-12, 3-1 and 3-6 using 10-methylphenothiazine) colours on another glass electrode coated with Indium Tin Oxide (ITO).

(106) The potential applied between both electrodes, for activating the compounds, is equal to the addition, in absolute value, of E.sup.1.sub.red of the compound+E.sup.1.sub.ox of phenothiazine (which is E.sup.1.sub.ox=0.36V) or methylphenothiazine (which is E.sup.1.sub.ox=0.45V).

(107) The absorption spectrum is read after 3 min of activation, in particular the λ.sub.max value, which corresponds to the maximum absorption peak within the visible spectrum (between 400 and 800 nm).

(108) The results for each of the synthesized compounds are indicated in Table 1 below. E.sup.1.sub.red corresponds to the first reduction potential. The colour indicated in Table 1 is the visual colour perceived by emmetropic eyes under day light conditions. It should be noted that the λ.sub.max value just gives an approximate indication of the colour of a particular compound. However, as a consequence of the broad nature of the absorption bands, the whole absorption spectrum has to be taken into account in order to understand the final perceived colour of any one compound.

(109) TABLE-US-00002 TABLE 1 Com- E.sup.1.sub.red λ.sub.max pound Molecule (V) (nm) Colour 1-1 / / blue 1-2 / / blue 1-3 −0.68 590 purple 1-4a 0 −0.78 / purple 1-4b / / purple 1-5 / / blue 2-1 −0.66 618 blue 2-2 −0.69 645 Blue green 2-3 −0.73 607 blue 2-4 −0.64 597 purple 2-5 −0.58 597 purple 2-6 −0.66 594 purple 2-7 −0.65 597 purple 2-8 0 −0.56 597 purple 2-9 −0.51 600 Purple 2-10 −0.57 594 Purple 2-11 −0.62 630 blue 2-12 −0.69 635 blue 3-1 −0.7 646 green 3-2 −0.63 625 Blue green 3-3 −0.6 630 green 3-4 −0.52 595 Blue- green 3-5 −0.66 640 green 3-6 0 −0.68 630 green 3-7 −0.68 599 blue 3-8 −0.61 630 Blue- green