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Title: Molecular mechanics approach for design and conformational studies of macrocyclic ligands

Computational Chemistry has revolutionized way of viewing molecules at the quantum mechanical scale by allowing simulating various chemical scenarios that are not possible to study in a laboratory. The remarkable applications of computational chemistry have promoted to design and test of the effectiveness of various methods for searching the conformational space of highly flexible molecules. In this context, we conducted a series of optimization and conformational searches on macrocyclic based ligands, 9N3Me5Ox, (1,4,7-tris(5-methyl-8-hydroxyquinoline)-1,4,7-triazacyclononane) and 12N3Me5Ox, (1,5,9-tris(5-methyl-8-hydroxyquinoline)-1,5,9-triazacyclododecane) and studied their selectivity and coordination behavior with some lanthanide metal ions in molecular mechanics and semiempirical methods. The methods include both systematic and random conformational searches for dihedral angles, torsion angles and Cartesian coordinates. Structural studies were carried out by using geometry optimization, coordination scans and electronic properties were evaluated. The results clearly show that chair-boat conformational isomer of 9N3Me5Ox ligand is more stable due to lower eclipsing ethane interaction and form stronger adduct complexes with lanthanide metal ion. This is because of the fact that, in a central unit of 9N3 of the ligand form six endo type bonds out of nine. The rest of bonds have trans conformation. In contrast, for the adduct of 12N3Me5Ox, two C-C bonds have on eclipsedmore » conformation, and others have synclinal and antiperiplanar confirmations. The distortion of the two eclipsed conformations may affect the yields and the stability of the complexes.« less
Authors:
; ;  [1]
  1. Department of Chemistry, Sant Longowal Institute of Engineering & Technology, Longowal-148106 (India)
Publication Date:
OSTI Identifier:
22488865
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1675; Journal Issue: 1; Conference: AMRP-2015: 4. national conference on advanced materials and radiation physics, Longowal (India), 13-14 Mar 2015; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; DODECANE; ETHANE; HYDROXY COMPOUNDS; ISOMERS; LIGANDS; MOLECULES; OXINE; PHASE STABILITY; QUANTUM MECHANICS; QUINOLINES; RARE EARTHS