New 2-cyano-N-(5-ethyl-1,3,4-thiadiazol-2-yl)acetamide (1) was utilized as a versatile precursor for the synthesis of various heterocycles, such as pyrrole, pyridine, coumarin, thiazole, pyrido[2′,3′:3,4]pyrazolo[5,1-c]triazine, triazolo[5,1-c]triazine, aminopyrazole, thiophene, 1,3-dithiolane, triazolo[1,5-a]pyrimidine and benzo[d]imidazole derivatives. The newly synthesized compounds were identified by IR, MS, ¹H NMR, ¹³C NMR, DEPT, H–H COSY, HMBC, and HSQC. Representative compounds of the synthesized products were examined and estimated as insecticidal agents against the cotton leafworm, Spodoptera littoralis.

We have synthesized new metal-free dyes (HB-1–8) containing bifuran/biphenyl derivatives for dye-sensitized solar cells. Dye HB-3 exhibited the highest efficiency among the eight investigated dyes, reaching 5.51% with aV_OCvalue higher than N3.

In this work, we studied the photovoltaic performance of two novel metal-free organic dyes (MR-3 and MR-4) with the molecular motif D–π–π–A carrying the same donor (trimethoxy benzene) and terthiophene (π) units but with different anchoring moieties. MR-3 and MR-4 displayed PCE of 4.54% and 2.38%, respectively. Furthermore, MR-3 co-sensitized with NCSU-10 exhibited improved efficiency of 9.09% than NCSU alone (8.74%). One of the merits in the studied structure motif D–π–π–A was modulating the molecular geometry of the sensitizers and eliminating the steric effect between the donor and π-spacer (terthiophene) to furnish a coplanar molecular structure and to maximize electronic conjugation. In addition, coupling-steric effect precludes effective conjugation and reduces light harvesting as it increases the band gap. To eliminate the steric effect of the aryl moiety at ortho position of 2,4,6-trimethoxyphenyl donor, another conjugated spacer, alkene (CHCH), was inserted between the donor and the π-spacer (terthiophene), which maximized the electron conjugation throughout the coplanar system; the optimized molecular geometry of the dyes was calculated using DFT. Another molecular geometry feature that was studied was the influence of different anchoring groups on coplanarity of the dye structure and consequently the photovoltaic performance. In the case of MR-3, where the anchoring group is based on the cyanoacrylic group, the optimized geometry was found coplanar. However, when rhodanine moiety was used as an anchoring group, the calculated optimized geometry of the dye (MR-4) was not coplanar, which resulted in weak electronic coupling and inferior electronic injection into TiO₂ conduction band edge. The inter-relationship between the optimized geometry of the dyes and their photovoltaic performance is discussed.

The photophysical and electrochemical properties of new targeted 2-cyanoacetanilide-based dyes are illustrated. New cyanoacetanilides SA7–10 were synthesized and employed as co-sensitizers in DSSCs. The chemical structures of these 2-cyanoacetanilides differ according to the substituent at the benzene ring (–H, –Me, –OMe and –NEt₂), with the anchoring moiety being the same, a –COOH group. Furthermore, a density functional theory (DFT) calculation has shown an effective intermolecular charge transfer character, the HOMOs of SA7–10 are mainly located on the corresponding donor part, and their LUMOs are located on carboxylic acid moieties as the acceptor. Interestingly, using photosensitizers SA7–10 as co-sensitizers with HD-2 dye causes an improvement in their photovoltaic performances. Among the dyes, SA10 co-sensitized with HD-2 displayed an overall efficiency of 8.25%, a J_SC of 19.5 mA cm⁻², a V_OC of 0.65 V and an FF of 64.35 compared to 7.46%, 19 mA cm⁻², 0.64 V and 60.54, respectively, of HD-2 only. Moreover, the electrochemical impedance spectroscopy (EIS) data of SA7–10 and HD-2 were found to be in accordance with the obtained photovoltaic parameters. Finally, the results indicated that 2-cyanoacetanilide-based dyes were utilized as promising co-sensitizers due to their easy preparation methods and their relatively small size.