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In this work, we present the synthesis of novel donor-acceptor compounds based on 3-methylquinoxaline-2(1 H )one which follow an easy synthetic route, involving Knoevenagel reaction with electron-donor groups such as N,N - dimethylaminobenzene, ferrocene, triphenylamine (TPA) and (( E )-4,4'-(ethene-1,2-diyl) bis ( N,N -diphenylaniline). Additionally, the optical properties were measured by means of the absorption and emission spectroscopy suggesting a push-pull behavior which was further confirmed by electrochemical experiments. Finally, the quinoxaline-2(1 H )one fragment not only bestow wide absorption, but also can chelate to titanium ions on the TiO 2 surface, allowing a strong electron coupling between the excited-state energy level of the dyes and the conduction band of TiO 2 . [ABSTRACT FROM AUTHOR]

• Three donor-acceptor compounds were designed and synthesized, and their structures were studied. • Compounds 1–3 exhibit photochromic properties and interesting photomodulated luminescence properties. • Compound 1 can be used as an ammonia vapor sensor. Synthesized three different supramolecular polymers, {[(4-BCBPY) 0.5 (H 2 BTEC) 0.5 ]·H 2 O} n (1), {[(4-BCBPY)(C 2 H 5 NO)C l ]·H 2 O} n (2) and {[(4-BCBPY)(C 2 H 5 NO)C l ]·H 2 O} n (3) (H 2 BTEC2− = 1,2,4,5-benzenetetracarboxylic acid anion). In compound 1 , benzene carboxylic acid anion acts as an electron donor, and electron-deficient viologen acts as an electron acceptor to form a supramolecular assembly. In compounds 2 and 3 , electron-deficient viologen forms supramolecular assemblies with N-methylformamide, water and chloride ions. All three compounds are connected through non-covalent interactions and form a donor-acceptor (D-A) system. Compounds 1, 2 and 3 all exhibited photochromic behavior of electron transfer, while also exhibiting interesting photomodulated luminescence behavior. And compound 1 can also be used as an ammonia vapor sensor material. The photochromic mechanism of the compound and the correlation between calculation and practice are deeply studied by using time-dependent density functional theory (TDDFT). [Display omitted] Three new supramolecular compounds {[(4-BCBPY) 0.5 (H 2 BTEC) 0.5 ]·H 2 O} n (1), {[(4-BCBPY)(C 2 H 5 NO)C l ]·H 2 O} n (2) and {[(4-BCBPY)(C 2 H 5 NO)C l ]·H 2 O} n (3) were synthesized using viologen ligands 4-BCBPY·2Cl (1,1′-bis(4-cyanobenzyl)-4,4′-bipyridinium dication) and H 4 BTEC as raw materials. The effects of metal salts and pH on the structures of the three compounds were studied. Under the irradiation of 350 W xenon lamp, the three compounds change from their original color to blue, which is caused by photo-generated viologen free radicals. Compounds 1, 2 and 3 also showed interesting photomodulated luminescence behavior. At the same time, compound 1 can be used as an ammonia vapor sensor. [ABSTRACT FROM AUTHOR]

• New acceptor and anchoring group based on hydantoin structure was synthesized. • The malononitrile moiety in the hydantoin core decreases the LUMO of the dyes. • Hydantoin moiety is used as a new anchoring group onto TiO 2. • Theorical calculations and experimental data demonstrated push-pull behavior of the dyes. • Functionalized hydantoin was efficiently linked to several electro-donor moieties. In this work, we present the synthesis of novel D-π-A compounds based on the structure of 2-(3-hexyl-2-oxoimidazolin-4-ylidene) malononitrile, which can function as an acceptor group and anchoring group to the TiO 2 surface. The synthetic route of the dyes involving a Knoevenagel condensation under microwave irradiation with donors based on triphenylamine (TPA) and thiophene moiety as a conjugated wire. Additionally, absorption, emission and electrochemical experiments were carried out to demonstrate a push-pull behavior in all the dyes. Finally, DCH 1-6 dyes were tested as photosensitizers in Grätzel type solar cells showing a low PCE values (between 0.10% and 0.60%), due to the poor electron injection on TiO 2 surface for the low LUMO energy levels of the prepared dyes. [Display omitted] [ABSTRACT FROM AUTHOR]