E. N. Shepelenko

Photochromic Cation Sensors

ABSTRACT Novel photochromic chemosensors for alkali-, alkali-earth and d-metal cations were synthesized and their photochemical and complexing properties investigated with the use of UV/vis, IR, 1H/7Li NMR spectroscopy and quantum chemical calculations – DFT(B3LYP/6-31G).

Synthesis of Novel Iono- and Photochromic Spiropyrans Derived from 6,7-Dihydroxy-8-Formyl-4-Methyl-2H-Chromene-2-One

�-hydroxy group were synthesized and their spectral properties as well as abilities for complexation with metal ions studied. In solutions they exist as equilibrium mixture of spirocyclic (A) and merocyanine (B) isomers. The largest content of merocyanine form was found for the derivative with an electron-donating methyl group in position 5 of hetaryl fragment. The irradiation of SPPs in acetonitrile shifts the equilibrium to the B form. Similar effect causes the addition of metal cations due to formation of colored complexes with merocyanine isomers.

Synthesis and photochromic properties of spiropyrans containing a fused benzopyranone fragment

New spiro compounds of the indole, phthalazine, isobenzofuran, and benzopyran series, containing a fused benzopyranone fragment in the chromene moiety, were synthesized. Indole derivatives were found to exhibit photochromic properties under stationary conditions at 293 K. The thermal stability of merocyanine isomers sharply decreases upon introduction of electron-withdrawing nitro group into the indole fragment and fusion of a benzene ring to the chromene fragment.

Chemosensors based on N -(9-anthrylmethyl)-benzene-1,2-diamine

A number of N-(9-antrylmethyl)-N′-arylmethylidenebenzene-1,2-diamines and 1-(9-anthrylmethyl)-2-aryl-1H-benzimidazoles were synthesized by condensation of N-(9-anthrylmethyl)benzene-1,2-diamine with aromatic and heterocyclic aldehydes. Study on their luminescent properties and complexing ability showed that 2-{[2-(9-anthrylmethylamino)phenylimino]methyl}-5-methylphenol, 2-{[2-(9-anthrylmethylamino)phenylimino] methyl}-4-methoxyphenol, and 2-{[2-(9-anthrylmethylamino)phenylimino]methyl}-6-methoxy-4-nitrophenol are effective and highly selective chemosensors for H+ and Hg2+ ions.

Benzoid-quinoid tautomerism of schiff bases and their structural analogs: LIII. Schiff bases derived from 5-hydroxy- and 5-hydroxy-6-nitro-2,3-diphenyl-1-benzofuran-4-carbaldehydes

Abstract4-Aryl(alkyl)iminomethyl-5-hydroxy-and 4-aryl(alkyl)iminomethyl-5-hydroxy-6-nitro-2,3-diphenyl-1-benzofurans were synthesized and were shown to exist in solution as equilibrium mixtures of benzoid and quinoid tautomers. The fraction of the quinoid form increases with rise in the solvent polarity and in going from N-aryl to N-alkyl derivatives; introduction of an electron-acceptor substituent (nitro group) into the 6-position of the benzofuran system also favors formation of the quinoid tautomer. Complex formation of alkali and alkaline-earth metal cations with the 5-hydroxy-6-nitro-2,3-diphenyl-1-benzofuran-4-carbaldehyde imine having a benzo-15-crown-5 fragment on the nitrogen atom is accompanied by specific changes in the luminescence spectrum and in the state of tautomeric equilibrium, so that this system may be regarded as tautomeric fluorogenic chemosensor for metal cations.

Synthesis and Photochromic Properties of Asymmetric Dihetarylethenes Based on 5-methoxy-1,2-dimethylindole and 5-(4-bromophenyl)-2-methylthiophene

We report the synthesis of new asymmetric dihetarylethenes – 4-[5-(4-bromophenyl)-2-methylthiophen-3-yl]-3-(5-methoxy-1,2-dimethyl-1H-indol-3-yl)furan-2,5-dione and 1-alkyl(phenyl)-3-(5-methoxy-1,2-dimethyl-1H-indol-3-yl)-4-[5-(4-bromophenyl)-2-methylthiophen-3-yl]-1H-pyrrole-2,5-diones, which exhibit photo-chromic and fluorescent properties in solution. Thermally stable photoinduced cyclic isomers were observed for dihetarylethenes derived from 5-methoxy-1,2-dimethylindole and 5-(4-bromophenyl)-2-methylthiophene, unlike for their structural analogs based on 5-methoxy-1,2-dimethylindole and unsubstituted thiophene. Changing the thiophene fragment of dihetarylethenes to a 5-(4-bromophenyl)-2-methylthiophene fragment gave rise to photochromic properties in furan-2,5-dione derivatives.

11-R-dibenzo[b,e][1,4]diazepin-1-ones, the chemosensors for transition metal cations

A series of 11-R-dibenzo[b,e][1,4]diazepin-1-ones was synthesized. The luminescence, complex formation, and redox properties of these compounds were investigated. The 11-(anthracen-9-yl)-3,3-dimethyl-2,3,4,5,10,11-hexahydro-1H-dibenzo[b,e][1,4]diazepin-1-one was found to be an effective and selective fluorescent chemosensor for Cd2+ cations.

Chemosensor properties of mono- and bisthioureas based on 9-anthrylmethyl-substituted alkylamines and diamines

Mono- and bisthioureas were synthesized based on N-(9-anthrylmethyl)-substituted alkylamines and diamines. Their luminescent and complexing properties were studied by the electronic, IR, and NMR 1H spectroscopy. N-(9-Anthrylmethyl)-N-(6-{9-anthrylmethyl[(phenylamino)carbothioyl]amino}hexyl)-N′-phenylthiourea was shown to be a highly effective fluorescent chemosensor for Hg2+ cations.

Chemosensors based on N-(2-aminophenyl)-N-(9-anthrylmethyl)amine: II

A series of N-(9-anthrylmethyl)arylimines was prepared by condensation of N-(2-aminophenyl)-N-(9-anthrylmethyl)amine with aromatic aldehydes. The study of the luminescent and complexing properties of compounds obtained showed that 2-{[2-(9-anthrylmethylamino)phenylimino]methyl}-1-naphthol and 1-{[2-(9- anthrylmethylamino)phenylimino]methyl}-6-bromo-2-naphthol were efficient highly selective chemosensors of cations Hg2+.

Ambident chemosensors based on benzo[h]chromen-2-one

Schiff bases derived from 7-hydroxy-4-methyl-2-oxobenzo[h]chromene-8-carbaldehyde in solution exist as equilibrium mixtures of benzoid and quinoid tautomers. The fraction of the quinoid tautomer increases with rise in solvent polarity. The Schiff base containing a benzo-15-crown-5 fragment on the nitrogen atom was shown to be a new ambident chemosensor capable of selectively binding transition metal cations via reaction at the o-hydroxyaldehyde imine fragment and alkaline-earth metals via host-guest interaction with the crown ether moiety. This compound exhibits a pronounced sensor activity toward Mg2+ and Ba2+ ions and is a selective naked-eye fluorescent chemosensor for Cu2+ and Co2+ ions.