A Novel Imidazole Bound Schiff Base as Highly Selective "Turn-on" Fluorescence Sensor for Zn2+ and Colorimetric Kit for Co2.

An imidazole based Schiff base (2-[(1H-imidazole-2-ylmethylene)-amino]-4-methyl-phenol) (IMP), with an imine unit, has been designed and characterized by various standard methods. The evaluation of the probe as a fluorogenic sensor for Zn2+ and a chromogenic sensor for Co2+ has been rationalized in terms of the PET mechanism. In the presence of Zn2+, a light yellow colored solution of IMP with maximum absorption of 364 nm becomes bright yellow with maximum absorption of 410 nm and a measurable fluorescent signal at 612 nm with bathochromic enhancement. The sensitivity of the fluorescent based assay (6.78 × 10-9 M) for Zn2+ is far below the limit in the World Health Organization (WHO) guidelines for drinking water (7.6 × 10-5 M) and therefore it is capable of being a practical system for the monitoring of Zn2+ concentrations in aqueous samples. Moreover, IMP showed a highly selective colorimetric response to Co2+ by displayed an obvious pink color upon addition of metal solution immediately without any interference from other ions. These results provide a new approach for selectively recognizing the two most important trace elements in the human body simultaneously, for Zn2+ by emission spectra and Co2+ by the naked eye.

Synthesis and Characterization of a Novel Heterocyclic Schiff Base and Development of a Fluorescent Sensor for Vitamin B12.

A heterocyclic Schiff base (MPDPI)was synthesized by the condensation reaction of 1-phenylisatin with 4,5-dimethylphenylene diamine. It was characterized by using spectroscopic methods including UV visible, Infrared, 1H-NMR, 13C-NMR and mass spectrometry. It acts as the fluorescent probe for the detection of Vitamin B12 (Vit.B12) which shows high selectivity over other species via dynamic quenching mechanism. It is also highly sensitive towards Vit.B12 with a detection limit of [Formula: see text]M and showed a linear concentration ranging from [Formula: see text] to [Formula: see text]. Effect of other coexisting species was also studied. The satisfactory results were also obtained in real samples.Since, there are only few reports on Vit.B12, development of selective fluorescent probes for Vit.B12 would be worthwhile.