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Context: We investigated the interaction between glycine and Li+ in water environment based on the Gly·Li+(H2O)n (n = 0–8) cluster. Our study shows that for Gly·Li+, Li+ binds to both carbonyl oxygen and amino nitrogen to form a bidentate structure, and the first three water molecules preferentially interact with Li+. For n = 0–5, the complexes of Gly·Li+(H2O)n exist in neutral form, and when the water number reached 6, the complex can coexist in neutral and zwitterionic form, then zwitterionic structures are dominant for n = 7, 8. The analyses by RDG, AIM, and ESP in conjunction with the calculated interaction energies show that the interaction between Li+ and Gly decreases gradually with the water molecules involved successively from n = 1 to 6 and then increases for n = 7–8. Additionally, the infrared spectra of Gly·Li+(H2O)n (n = 0–8) are also calculated. Methods: The initial structures were optimized using Gaussian 09 program package in B3LYP-D3 (BJ)/6-311G(d, p) method, and the frequency was calculated with 6–311 + G(2d, p) basis set. GaussView5.0.9 was used to view simulation infrared spectra. The noncovalent interaction method (NCl), energy decomposition (EDA), atoms in molecules (AIM) analysis, and electrostatic potential (ESP) analyses were conducted using Multiwfn software to gain a deeper understanding of the interaction properties of Gly, Li+, and water. [ABSTRACT FROM AUTHOR]

Abstract A novel "turn-off" micellar self-assembled fluorescent chemosensor for detecting Pb2+ ions based on calix[4]arene derivative was prepared through self-assembly of amino thiadiazole calix[4]arene derivative (AMT-CA) as receptor, pyrene as fluorophore and trimethyltetradecylammonium bromide (TTAB) as template in aqueous solution. The fluorescence of pyrene was quenched by Pb2+ ions owing to the close proximity of the AMT-CA-Pb2+ complex to the pyrene based on fluorescent internal filter effect (IFE). The effects of pH value, concentration of TTAB and pyrene, molar ratio of AMT-CA/pyrene on the fluorescent chemosensor were studied. Further, the linear response for Pb2+ ions was in the range of 2–52 μmol/L. And Pb2+ ions can be selectively detected in the presence of cations (Ca2+, Mg2+, K+, Na+, Al3+, Zn2+, Ba2+, Cd2+) and anions (CH 3 COO−, Br−, Cl−, SO 4 2−, NO 3 −). Other similar micellar self-assembled fluorescent chemosensor with selective detection for other ions will be researched and developed based on calix[4]arene. Graphical abstract Unlabelled Image Highlights • A novel Pb2+-selective micellar self-assembled fluorescent chemosensor was prepared. • This fluorescent chemosensor could directly detect Pb2+ in aqueous solution. • Linear response for Pb2+ was in the range of 2–52 μmol/L. • This fluorescent chemosensor showed high selectivity towards Pb2+. [ABSTRACT FROM AUTHOR]