New 2-pyridone-based donor-acceptor dyes: the effect of the donor group position, type of π-linker and acid-base characteristics of the medium on the photophysical properties.

A series of novel donor-acceptor pyrid-2-ones was synthesized. The influence of the donor group on the photophysical properties of chromophores in solution was shown by varying the methoxy group position in the electron-rich aromatic ring. The effect of the π-linker was also demonstrated by the comparison of the D-π-A pyridone with its spacer-free analogue (D-A) and with the chromophore bearing an additional thiophene bridge (D-π-π-A). It was found that the presence of a π-linker plays a crucial role in the implementation of an intramolecular charge transfer (ICT) from the donor aryl moiety to the pyridone acceptor. Thus, for the synthesized D-A, D-π-A and D-π-π-A derivatives, the photoluminescence quantum yield in DMSO solution decreases from 56.8 to 4.3 and 3.5%, respectively, along with a strong bathochromic shift both for absorption (66 nm) and emission (162 nm) bands. Also, the possibility of shifting the equilibrium in DMSO solution towards either the pyridone form or the anionic form by the addition of a strong acid (TFA) and base (DBN) respectively was shown. Drastic changes in the photoluminescence of the solutions showed prospects for the application of the synthesized donor-acceptor pyridone derivatives as naked-eye acid-base indicators in organic media.

Tunable full-color emission of stilbazoles containing a 2-halo-3,4-dicyanopyridine acceptor.

Synthesis of a series of novel push-pull stilbazole-based chromophores containing a strong 2-halocinchomeronic dinitrile acceptor is reported. The photophysical properties of the compounds are described. Strong positive solvatofluorochromism typical of intramolecular charge transfer (ICT) dyes is observed for the synthesized stilbazoles. Their tunable multicolor emission ranges from 442 nm to 710 nm and covers the whole visible spectrum.

The synthesis of ortho-stilbazoles (2-styrylpyridines) (microreview).

This microreview compiles methods for the synthesis of ortho-stilbazoles (2-styrylpyridines) described in the literature in 2017-2022. Depending on the synthons from which the target structure is formed, four main synthetic approaches can be distinguished: coupling reactions, Wittig reactions, condensation reactions, and pyridine ring formation reactions.

Dual-State Emission of 2-(Butylamino)Cinchomeronic Dinitrile Derivatives.

New representatives of 2-(butylamino)cinchomeronic dinitrile derivatives were synthesized as promising fluorophores showing dual-state emission. To characterize the influence of the length (from methyl to butyl) and the structure (both linear and branched) of the alkyl substituent at the amino nitrogen atom, the spectral fluorescence properties of all synthesized compounds were carefully studied both in solution and in solid state. The highest photoluminescence quantum yield values of 63% were noted for solutions of 2-(butylamino)-6-phenylpyridine-3,4-dicarbonitrile in DCM and 2-(butylamino)-5-methyl-6-phenylpyridine-3,4-dicarbonitrile in toluene.

Synthesis and Chemosensory Properties of New Cyanosubstituted 2,2'-Bipyridine Derivatives.

A series of novel 6-oxo-1,6-dihydro-[2,2'-bipyridine]-5-carbonitriles has been synthesized and characterized. Their photophysical properties in DMSO solution and aqueous medium as well as fluorescence response to the presence of metal ions have been investigated. The obtained 4-(4-methoxyphenyl)-6-oxo-1,6-dihydro-[2,2'-bipyridine]-5-carbonitrile has been shown as a selective fluorescent "turn-ON" probe for Cd2+ ions with LoD 0.359 µM, 1:1 metal-ligand ratio and binding constant of 5.2 × 104 M-1.

Diastereoselective synthesis of 3,4-dihydro-2H-pyran-4-carboxamides through an unusual regiospecific quasi-hydrolysis of a cyano group.

An efficient diastereoselective approach for the synthesis of functionalized 3,4-dihydro-2H-pyran-4-carboxamides with variable frame was developed based on the reaction of available 4-oxoalkane-1,1,2,2-tetracarbonitriles (adducts of TCNE and ketones) with aldehydes in an acidic media. An unusual process of quasi hydrolysis of the cyano group was observed in the course of the described regio- and diastereoselective transformation.

Diastereoselective Cascade Assembly of Functionalized Pyrano[3,4-c]pyrrole Derivatives.

A novel convenient approach for the synthesis of densely functionalized pyrano[3,4-c]pyrrole derivatives was developed. Cascade transformation of the simple adducts of tetracyanoethylene (TCNE) and ketones (4-oxoalkane-1,1,2,2-tetracarbonitriles) in the presence of aldehyde under the action of acetic acid led to the diastereoselective formation of targeted pyrano[3,4-c]pyrroles. The reaction pathway was thoroughly investigated, and proposed intermediates were shown to be consistent with experiment.

Comparative in vivo evaluation of polyalkoxy substituted 4H-chromenes and oxa-podophyllotoxins as microtubule destabilizing agents in the phenotypic sea urchin embryo assay.

A series of polyalkoxy substituted 7-hydroxy- and 7-methoxy-4-aryl-4H-chromenes were evaluated using the sea urchin embryo model to yield several compounds exhibiting potent antimitotic microtubule destabilizing activity. Data obtained by the assay were further confirmed in the NCI60 human cancer cell screen. The replacement of methylenedioxy ring A and lactone ring D in podophyllotoxin analogues by 7-methoxy, 2-NH2, and 3-CN groups in 4-aryl-4H-chromenes resulted in potent antimitotic microtubule destabilizing agents. Feasible synthesis and high yields render 7-methoxy-4H-chromenes to be a promising series for further anticancer drug development.

The twofold interpenetrated three-connected three-dimensional (10,3)-net in 2-aminoethene-1,1,2-tricarbonitrile.

In the crystal structure of the title compound, C5H2N4, each molecule is linked by N-H...N[triple-bond]C hydrogen bonds to four other molecules, thus forming a network that can be described as a twofold interpenetrated three-connected three-dimensional (10,3)-net. The interpenetrated nets are related by (010) translation. If only intermolecular hydrogen bonds are taken into account, these nets can be considered as independent. However, the interactions between the cyano groups from different nets indicate mutual assistance of the two nets during their formation.