Synthesis of Novel Asymmetric Bis-Hydrazone Compounds Containing Indenoquinoxaline and Phenolic Moieties and Colorimetric Investigation of Chemosensing Properties for Various Ionsties and Colorimetric Investigation of Chemosensing Properties for Vari

Novel three asymmetric bis-hydrazone compounds, 2-(11H-indeno[1,2-b] quinoxaline-11-ylidene)hydrazone)methyl)phenol, 4-(11H-indeno[1,2-b]quinoxalin-11-ylidene)hydrazone) methyl)benzene-1,3-diol, 1-(11H-indeno[1,2-b]quinoxalin-11-lidene)hydrazone)methyl)naphthalen-2-ol, containing indenoquinoxaline and phenolic moieties as sensors (5a-c), were designed and synthesized in high yield (82-87%). Their structures were characterized by FT-IR, 1H NMR, 13C NMR, and MS spectroscopic methods. Their colorimetric sensor properties were investigated, and changes in the absorption of the UV-vis spectrum when interacting with some anions and cations in aqueous acetonitrile solution, as well as a well-defined color change detectable with the naked eye, were observed. While no change was observed with the addition of anions such as Cl–, Br–, I‒, SCN‒, OCl‒, HSO4‒, H2PO4‒, HPO42– and PO43– to the host solution (5a-c), the addition of the F‒, CN‒, OH‒, and OAc‒ anions was resulted with a red shift of the charge-transfer absorbance band accompanied by a color change from light yellow to purple-blue. In addition, the sensing behavior of receptors for different metal ions, such as Cu2+, Ni2+, Zn2+, Co2+, Mn2+, Pb2+, Fe2+, Fe3+, Hg+2, Ag+, and Sn2+ in aqueous acetonitrile solution was investigated, and they showed receptor properties against Cu2+, Ni2+, Co2+, and Zn2+ ions among them.