title: Computational evaluation of unsaturated carbonitriles as neutral receptor model for beryllium(II) recognition.
abstract: Design of neutral receptor molecules (ionophores) for beryllium(II) using unsaturated carbonitrile models has been carried out via density functional theory, G3, and G4 calculations. The first part of this work focuses on gas phase binding energies between beryllium(II) and 2-cyano butadiene (2-CN BD), 3-cyano propene (3-CN P), and simpler models with two separate fragments; acrylonitrile and ethylene. Interactions between beryllium(II) and cyano nitrogen and terminal olefin in the models have been examined in terms of geometrical changes, distribution of charge over the entire π-system, and rehybridization of vinyl carbon orbitals. NMR shieldings and vibrational frequencies probed charge centers and strength of interactions. The six-membered cyclic complexes have planar structures with the rehybridized carbon slightly out of plane (16° in 2-CN BD). G3 results show that in 2-CN BD complex participation of vinyl carbon further stabilizes the cyclic adduct by 16.3 kcal mol(-1), whereas, in simpler models, interaction between beryllium(II) and acetonitrile is favorable by 46.4 kcal mol(-1) compared with that of ethylene. The terminal vinyl carbon in 2-CN BD rehybridizes to sp (3) with an increase of 7 % of s character to allow interaction with beryllium(II). G4 calculations show that the Be(II) and 2-CN BD complex is more strongly bound than those with Mg(II) and Ca(II) by 98.5 and 139.2 kcal mol(-1) (-1), respectively. QST2 method shows that the cyclic and acyclic forms of Be(II)-2-CN BD complexes are separated by 12.3 kcal mol(-1) barrier height. Overlap population analysis reveals that Ca(II) can be discriminated based on its tendency to form ionic interaction with the receptor models.
authors.affiliation: Department of Chemistry, Faculty of Science Building, University of Malaya, Kuala Lumpur, 50603, Malaysia, nazmi86@siswa.um.edu.my.
authors.forename: Ahmad Nazmi
authors.initials: AN
authors.lastname: Rosli
authors.forename: Mohd Rais
authors.initials: MR
authors.lastname: Ahmad
authors.forename: Yatimah
authors.initials: Y
authors.lastname: Alias
authors.forename: Sharifuddin Md
authors.initials: SM
authors.lastname: Zain
authors.forename: Vannajan Sanghiran
authors.initials: VS
authors.lastname: Lee
authors.forename: Pei Meng
authors.initials: PM
authors.lastname: Woi
mesh_terms: D000181:Acrylonitrile / Q000737:chemistry; D001608:Beryllium / Q000737:chemistry*; D002070:Butadienes / Q000737:chemistry; D003198:Computer Simulation; D017076:Computer-Aided Design; D015195:Drug Design; D005030:Ethylenes / Q000737:chemistry; D007476:Ionophores / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D015394:Molecular Structure; D009570:Nitriles / Q000737:chemistry*; D011407:Propane / Q000031:analogs & derivatives / Q000737:chemistry; D013329:Structure-Activity Relationship
chemical_list: C570415:3-cyanopropene; D002070:Butadienes; D005030:Ethylenes; D007476:Ionophores; D009570:Nitriles; C036216:ethylene; D000181:Acrylonitrile; D001608:Beryllium; D011407:Propane