Hydrazinopyrimidine derived novel Al3+ chemosensor: molecular logic gate and biological applications

Abstract

Cost-effective and highly sensitive biocompatible probes for the detection of Al³⁺ have tremendously important practical applications. Herein, we report for the first time, the hydrazinopyrimidine based Al³⁺ chemosensor L (1-[(4,6-dimethyl-pyrimidin-2-yl)-hydrazonomethyl]-naphthalen-2-ol) prepared by the condensation of 2-hydroxy-1-naphthaldehyde and 4,6-dimethyl-2-hydrazino-pyrimidine. Our as-synthesized chemosensor L (Φ = 0.0066) shows ∼15 fold fluorescence enhancement in the presence of Al³⁺ (Φ = 0.0955, K_a = 1.9 × 10⁴ M⁻¹) via chelation enhanced fluorescence (CHEF), excited state intramolecular proton transfer (ESIPT), and inhibited photo-induced electron transfer (PET) phenomena. The limit of detection (LOD) and limit of quantification (LOQ) were estimated to be 2.78 μM and 9.27 μM, respectively. Furthermore, for the first time, a hydrazino pyrimidine based ‘INHIBIT’ molecular logic gate for Al³⁺ was successfully developed using the fluorescence properties of L. The experimental sensing mechanisms of L for Al³⁺ were corroborated by theoretical calculations. Biocompatibility and good water-solubility properties of a pyrimidine moiety of L inspired us to investigate Al³⁺ imaging in human embryonic kidney cell lines, HEK293, and the results for practical applications are highly promising.