L. L. Popova

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.

Synthesis and photochromic properties of 4-[2-(anthracen-9-yl)-5-methyloxazolyl] fulgide

New photochromic fulgide, viz., 4-{1-[2-(anthracen-9-yl)-5-methyloxazol-4-yl]ethylidene}-3-isopropylidenetetrahydrofuran-2,5-dione, with fluorescent properties was synthesized. Studies by electronic, IR, and 1H NMR spectroscopy and X-ray diffraction demonstrated that this fulgide exists in the Z form. Light irradiation of its solutions at a wavelength of 365 nm causes Z/E isomerization giving rise to the thermally stable cyclic form. The latter is transformed into the starting E isomer under light irradiation at λ = 436 nm.

Benzoid-Quinoid Tautomerism of Schiff Bases and Their Structural Analogs: LII.* Schiff Bases Derived from 6-tert-Butyl-5-hydroxy- and 5-Hydroxy-6-iodo-2,3-tetra-methylenebenzo[b]furan-4-carbaldehydes

Two series of Schiff bases, 4-aryl(alkyl)iminomethyl-6-tert-butyl-5-hydroxy- and 4-aryl(alkyl)iminomethyl-5-hydroxy-6-iodo-2,3-tetramethylenebenzo[b]furans were synthesized. These compounds in solution give rise to tautomeric benzoid-quinoid equilibrium; the fraction of the quinoid form in the equilibrium mixture increases with rise in solvent polarity and in going from N-aryl to N-alkyl derivatives. The benzoid tautomer shows fluorescence with an anomalous Stokes shift. The absorption and luminescence spectral properties of the examined Schiff bases make them promising as signal fragments of chemosensors for metal cations.

Benzoid-Quinoid Tautomerism of Schiff Bases and Their Structural Analogs: LI. Photoacylotropic Enaminoketones with a Fluorophoric Migrant

The acylation of ortho-substituted (R = OH, OMe, NHTs) 2-arylaminomethylene-2,3-dihydro- benzo[b]thiophen-3-ones with (4-methyl-2-oxobenzo[b]pyran-7-yloxy)acetyl chloride results in formation of the corresponding N-acyl enaminoketones. The same reaction with 2-(2-hydroxyphenylaminomethylene)-2,3- dihydrobenzo[b]thiophen-3-one gives rise to a tautomeric mixture of acyloxyphenyl and N-acyl enaminoketone isomers. Irradiation at a wavelength corresponding to the absorption region of the N-acyl enaminoketone isomer leads to N→O acyl group transfer to afford O-acylated isomer. The complex formation ability of all tautomeric forms with respect to Zn2+ and Ni2+ cations and their fluorescence properties were studied.

Synthesis and photochromic properties of fulgides and fulgimides, 5-alkoxybenzo[ b ]furan derivatives

New heterocyclic fulgides, 3-[1-(5-alkoxy-2-methylbenzo[b]furan-3-yl)ethylidene]-4-(2-propylidene)dihydro-2,5-furandiones, and fulgimides, 1-(2-dimethylaminoethyl)-3-[(5-methoxy-2-methylbenzo[b]furan-3-yl)ethylidene]-4-(2-propylidene)dihydro-2,5-pyrroledione and 1-benzyl-3-[(5-methoxy-2-methylbenzo[b]furan-3-yl)ethylidene]-4-(2-propylidene)dihydro-2,5-pyrroledione, were synthesized. Electron spectroscopy and 1H NMR spectroscopy were used to establish that all the compounds obtained have Z-configuration and exhibit photo-chromic properties with high stability to photodegradation in solutions. Cyclic photoisomers of fulgides possess fluorescent properties and thermal stability.

Synthesis and photochromic properties of fulgides based on naphtho[1,2-b]furan and benzo[g]indole

Heteroaromatic fulgides and fulgimides are among the most promising photochromic compounds for three-dimensional optical data storage devices and optical molecular switches due to high stability of their initial and photoinduced forms [1, 2]. However, there are no data on fulgides based on naphtho-fused fivemembered heterocyclic compounds. With the goal of studying compounds of this sort, we have synthesized fulgides IIa and IIb by the Stobbe condensation of 1-(5-methoxy-2-methylnaphtho[1,2-b]furan-3-yl)ethanone (Ia) and 1-(5-methoxy-2-methyl-1-phenyl1H-benzo[g]indol-3-yl)ethanone (Ib) with diethyl 2-isopropylidenebutanedioate in the presence of sodium hydride [3] (Scheme 1). On the basis of the IR and H NMR spectra, the isolated products were assigned the structure of 3-isopropylidene-4-{1-(5-methoxy-2-methylnaphtho[1,2-b]furan-3-yl)ethylidene}tetrahydrofuran-2,5-dione (IIa) and 3-isopropylidene-4-{1-(5-methoxy-2-methyl-1phenyl-1H-benzo[g]indol-3-yl)ethylidene}tetrahydrofuran-2,5-dione (IIb). Both compounds are E isomers with respect to the C=C hetarylethylidene double

Photochromic benzo[g]indolyl fulgimide with modulated fluorescence

A new photochromic fulgimide, (E)-1-(anthracen-9-ylmethyl)-3-[1-(5-methoxy-2-methyl-1-phenyl-1H-benzo[g]indol-3-yl)ethylidene]-4-(propan-2-ylidene)pyrrolidine-2,5-dione, has been synthesized and found to exhibit fluorescence. The structure of this compound and intermediate fulgenates and amidofulgenic and fulgenic acids has been determined by electronic and vibrational spectroscopy, 1H and 13C NMR, and mass spectrometry. The amidofulgenic and fulgenic acids are capable of undergoing photoinduced reversible Z/E isomerization with respect to the C=C bond without subsequent cyclization, whereas fulgenates are converted to the corresponding cyclic structures. The new fluorescent fulgimide is transformed into the colored nonfluorescing cyclic isomer under UV irradiation. The reverse ring opening under visible light irradiation restores the fluorescence properties, which makes this compound a molecular fluorescence switch.

Photoinduced Acylotropic Rearrangement of Crown-Containing 2-[N-Acetyl-N-(4-aminobenzo-15-crown-5)methylene]-2,3-dihydrobenzo[b]thiophen-3-one

Abstract2-N-(4-Aminobenzo-15-crown-5)methylene-2,3-dihydrobenzo[b]thiophen-3-one and its acetyl derivative were synthesized. Their treatment with lithium, sodium, or potassium iodide in acetonitrile solution leads to formation of the corresponding crown-metal complexes. Irradiation of the acylated compounds at λ 436 nm induces NO migration of the acetyl group to give O-acyl isomer which is characterized by a considerable blue shift of the long-wave absorption band (Δλ = 70 nm). The quantum yields of the photo- induced acylotropic reaction for the free ligand and its complexes with alkali metal cations change in the series: ϕL > ϕK+ > ϕNa+ > ϕLi+.