Experimental and computational anion binding studies of meso-substituted one-walled phthalimide-based Calix[4]pyrrole

• Published in: Journal of molecular structure Vol. 1280; p. 135065
• Main Authors: Rather, Ishfaq Ahmad, Riaz, Ufana, Ali, Rashid
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.05.2023
• Subjects: Anion binding; Calixpyrrole; Computational studies; deep eutectic solvent (DES); Phthalimide; Anion binding; Computational studies; Calixpyrrole; deep eutectic solvent (DES); Phthalimide
• ISSN: 0022-2860; 1872-8014
• DOI: 10.1016/j.molstruc.2023.135065

•Phthalimide one walled C4P (m-PC4P) was prepared for anion binding studies.•UV–vis spectroscopy and DFT studies ensured binding of halides and nitrate ion.•m-PC4P offer 1:1 binding mode and higher anion binding affinities compared to C4P.•NH-hydrogen bonding and CH-anion interactions govern higher binding affinity.•Anion binding affinity decreases with increase in size of halide ions. Anion binding studies of meso‑substituted one-walled phthalimide-based calix[4]pyrrole (m-PC4P, 6) were investigated through UV–vis spectroscopy in acetonitrile and corroborated by time-dependent density functional theory (TD-DFT) calculations using 6–311G(d) basis set. Notably, to our expectation, the m-PC4P (6) displayed higher anion binding affinities in comparison to the parent C4P system, probably due to the additional weak CH-anion interactions besides four NH-hydrogen bonds of the C4P framework (supported by 1H NMR evidence). Herein, we have observed the usual trend with halide anions (used as their tetrabutylammonium salts), i.e. with increase in size of the halides from fluoride to iodide, the anion binding affinity decreases. Moreover, with the nitrate anion, appreciable better binding was observed in the case of m-PC4P (6) as compared to the simple C4P (1). [Display omitted]