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A fluorenyl-thioic-based dye (P) bearing a thioic ester moiety was designed, synthesized and spectroscopically characterized. The photophysical properties were studied via UV–Vis spectroscopy in acetonitrile (CH3CN) as a solvent of choice. Upon investigating and studying the photophysical properties, it was found that P could be an ideal colorimetric sensor for biologically important anions and cations. The chemosensing properties were studied through naked eye observable colour changes as well as UV–Vis titration method. The naked eye observations and UV–Vis titrations established that P is a colorimetric probe selective and sensitive to some cations (Ag+, Hg2+, Ni2+, Fe3+, Co2+, Cu2+ and Zn2+) and anions (F−, CN−, OH− and AcO−) in CH3CN. The nature of interaction with cations is via coordination by soft atoms (nitrogen and sulphur atoms), in the process inducing spectral red shift (375 to 475 nm), whereas interaction with anions was dominated by hydrogen bonding, leading to yet another red shift (375 to 453 nm). The cross-detection studies have indicated that M has more affinity towards Cu2+, followed by Zn2+, compared to all other cations used. The reversibility and reproducibility studies were carried out, and P was found to exhibit molecular logic behaviours, thereby displaying complementary IMP/INH logic functions, based on colour and spectral switching (ON/OFF). Hence, the probe can thus be utilized as a colorimetric molecular switch modulated by F−/Al3+. In addition, the experimental data were supplemented by computational calculations, where HOMO and LUMO levels at − 5.65 and − 2.51 eV (3.14 eV energy gap) for P were well in agreement with the absorption curve. [ABSTRACT FROM AUTHOR]

In this study, a new chemosensor IDTTH for rapid detection of cyanide (CN─) based on 6,6,12,12-Tetrakis(4-hexylphenyl)-6,12-dihydrodithieno[2,3-d:2′,3′-d′]-s-indaceno[1,2-b:5,6-b′]di- thiophene-2,8-dicarboxaldehyde-hemicyanine conjugate has been developed. The 6,6,12,12-tetrakis(4-hexylphenyl)-6,12-dihydrodithi-eno[2,3-d:2′,3′-d′]-s-indaceno[1,2-b:5,6-b′]dithiophene was served as a signal unit and hemicyanine as a recognition unit. This probe shows high selectivity towards CN─ ions among tested anions. Addition of CN─ ions to probe IDTTH in semi-aqueous solution (acetonitrile/H2O = 1/1, V/V) could lead to a 195 nm blue shift of absorption band, together with colour changes from blue to yellow. The sensing mechanism is attributed to the nucleophilic addition between CN─ and the C=N bond of indolium group, which could be clearly clarified through the 1H NMR titration and MS spectral. Moreover, probe IDTTH could be used as the test strips with low cost to detect CN─ ions conveniently by naked eyes. [ABSTRACT FROM AUTHOR]