A smart molecular probe for selective recognition of nitric oxide in 100% aqueous solution with cell imaging application and DFT studies.

Herein, a simple, least-cytotoxic as well as an efficient fluorescent sensor HqEN480 was prepared from (quinolin-8-yloxy)-acetic acid ethyl ester (L1) and N,N-dimethylethylene diamine to recognize NO in 100% aqueous solution. Its marked selectivity and sensitivity towards NO, makes it a highly suitable probe for nitric oxide under in vitro conditions with the possibility of in vivo monitoring of NO. Upon addition of 3.5 equivalents of NO, there is an approximately 7 fold enhancement in fluorescence intensity in aqueous solution with a corresponding Kf value of (1.75 ± 0.07) × 104 M-1. Quantum yields of HqEN480 and [HqEN480-NO] compounds are determined to be 0.04 and 0.22, respectively, using acidic quinine sulphate as a standard. In terms of the 3σ method, the LOD for nitric oxide was found to be 53 nM thus, making the probe suitable for tracking NO in biological systems.