Micro-solvation of the Zn2+ ion—a case study

Abstract

The structures and thermodynamic parameters of hydrated zinc ion clusters incorporating a single zinc ion and up to eighteen water molecules have been determined with a quantum mechanical hybrid density functional, namely B3LYP using cc-PVDZ basis functions for H and O and a split valence 6-31G (d, p) basis function for Zn. The geometries for all the zinc ion water clusters are optimized with several initial guess structures and without imposing any initial symmetry restriction. Zinc metal ion is found to be preferably four coordinated for smaller sizes of hydrated cluster but attains an octahedral coordination for larger sizes (n >or= 11) of hydrated cluster. Structures with seven or more than seven water molecules attached directly to the central zinc ion are not found. The calculated gas phase coordination number in the first solvation sphere of a large hydrated zinc metal ion is found to be six and the same is also confirmed in the force field based classical molecular dynamics simulation study for an aqueous zinc ion and thus confirms the experimental findings. The equilibrium zinc-oxygen distance of 2.09328 A at the present B3LYP level of study is in excellent agreement with the X-ray diffraction result of 2.093 +/- 0.002 A for a hexahydrated zinc cluster.

Effect of Na+, Mg2+, and Zn2+ chlorides on the structural and thermodynamic properties of water/n‐heptane interfaces

“…The second peak describes a second solvation shell formed by 11.75 water molecules, which is again slightly underestimated compared with the experimental data measured in water solution (12) 52. The zinc cation presents a first solvation sphere formed by approximately six water molecules, whereas its second solvation shell is formed by 12 water molecules, in agreement with the most widely accepted values for Zn 2+ in water solution 53–57. In the latter case, water structure and dynamics are only perturbed in a short range 50, 58–60.…”

Preferential interaction of charged alkali metal ions (guest) within a narrow cavity of cyclic crown ethers (neutral host): A quantum chemical investigation

“…In case of Li + A9C3 complexes, the least stable free conformer (9C3-I) has become more stable than the more stable conformer (9C3-II) by 7.9 kcal/mol after complexation with lithium metal ion. Note, that various conformers of 12C4ALi + complexes are not discussed here as those were reported elsewhere [58]. The most stable free conformer (15C5AI) of 15C5 is now relatively less stable than the least stable structure (15C5-III) after complex formation Table 1 Calculated values of different structural and energy parameters of free crown ether ligand (L) at B3LYP level of theory using 6-311++G(d,p) basis function for all the elements.…”

“…In case of Na + A9C3 complexes, the least stable free conformer (9C3-I) has become more stable than the more stable conformer (9C3-II) by 11.29 kcal/mol after complexation with sodium metal ion. Note, conformers of 12C4ANa + complexes were reported elsewhere [58]. Three minimum energy structures have been found for Na + A15C5 complexes.…”

“…Thermal corrections to the electronic energy (E el ), enthalpy (H) and free energy (G) of the optimized free crown ethers and metal ion-crown ether complexes have been performed following the earlier reported procedure [57,58]. The total internal energy (U) of free crown ethers and metal ion-crown ether complexes is obtained after adding the correction term (CT) to the electronic energy as…”

Ο Ρόλος Των Διαλυτών Στη Διαμόρφωση Των Πεπτιδίων

“…[122,123] Για την περαιτέρω διερεύνηση της ενυδάτωσης των παραπάνω βιομορίων, τοποθετήθηκαν σταδιακά και τυχαία ξεχωριστά μόρια νερού γύρω από τα υπό μελέτη βιομόρια, ενώ παράλληλα χρησιμοποιήθηκε η επίδραση του bulk διαλύτη 5 . [54,124] Ο απώτερος σκοπός ήταν η πρόβλεψη της δομής μιας πρώτης σφαίρας επιδιαλύτωσης των υπό μελέτη βιομορίων, επιδεικνύοντας τον μέγιστο αριθμό μορίων νερού που μπορούν άμεσα (μέσω δεσμών υδρογόνου) να αλληλεπιδράσουν με τα παραπάνω μόρια και να διαπιστωθούν τυχόν αλλαγές στον αριθμό τους από την πρωτονιομένη στην ουδέτερου pH κατάσταση των αμινοξέων, ακέτυλο αμινοξέων και βεταϊνών.…”