Neutral water clusters

Shields, G.C., Kirschner, K.N. The limitations of certain density functionals in modeling neutral water clusters. Synthesis Reactivity Inorg. Metal-Organic Nano-Metal Chem. 2008, 38(1), 32-6. 

A water molecule favors four H-bond interactions. Neutral water clusters are determined mainly by the H-bond interactions and strains between water molecules. Structures, energetics, and electronic and spectroscopic properties of small water clusters have been well investigated [13-15]. Each water molecule in... 

Figure 1. The lowest-energy neutral water cluster structures (W2 i2 at 0 K) and four other iso-energetic isomers of neutral water hexamer.

Table 1. Interaction energies (kcal/mol) of neutral water clusters (H20) 2-i2 ...

Fig. 34.1. Calculated minimum energy structures of the neutral water cluster stmctures. More details on these...

In addition to the red shifts observed in case of the -OH stretching modes, the HOH bending modes of the neutral water clusters display characteristic blue shifts with respect to that of the pure water monomer. Thus a transition from da to dda type leads to an increase in the blue shifts, with the dda waters in the hexamer and heptamer cages and cubic T>2d conformers exhibiting the largest shifts 120 cm ) for the bending modes. 

The structures of aqueous clusters formed by the interaction of a cation, an electron, or an anion, with various sizes of water clusters bear no structural resemblance to the parent neutral water clusters because of the dominance of electrostatic interactions. However, things are very different in the case of interactions involving ir-systems with varying sizes of water clusters. This is because of the fact that the interactions existing between... 

B. Hartke, Size-dependent transition from all-surface to interior-molecule structures in pure neutral water clusters, Phys. Chem. Chem. Phys. 5 2 (2003), pp. 275-284. 

A weakly dipole-bound cluster anion that predominates when an extra electron is attached to a cold, equilibrated, neutral water cluster. 

Anion solvation in alcohol clusters has been studied extensively (see Refs. 135 and 136 and references cited therein). Among the anions that can be solvated by alcohols, the free electron is certainly the most exotic one. It can be attached to neutral alcohol clusters [137], or a sodium atom picked up by the cluster may dissociate into a sodium cation and a more or less solvated electron [48]. Solvation of the electron by alcohols may help in understanding the classical solvent ammonia and the more related and reactive solvent water [138], By studying molecules with amine and alcohol functionalities [139] one may hope to unravel the essential differences between O- and N-solvents. One should note that dissociative electron attachment processes become more facile with an increasing number of O—H groups in the molecule [140],... 

The monolayer formed by 6-dodecyl-2-naphthol [192] on neutral water shows no fluorescence due to the DP form at 420 nm. The absence of a water-cluster-base [33-37], and a reduction of apparent surface dielectric constant have been offered as explanations of this observation. A similar observation of the absence of excited DP form fluorescence was made in Langmuir-Blodgett (LB) films of... 

Some problems remain regarding the neutralization rates of the ions since although the dissociative recombination coefficients, o, of the positive ions, including the water cluster ions, have been reasonably well studied estimate have to be made for are for several important reactions as yet not studied. Similarly, although mutual neutralization rate coefficients, ari, appear to be largely independent of the nature of the ions even when they are relatively big clusters, ari should still be determined for the larger clusters now known to exist in the atmosphere. 

C. P. Kelly, C. J. Cramer and D. G. Truhlar, SM6 A density functional theory continuum solvation model for calculating aqueous solvation free energies of neutrals, ions, and solute-water clusters, J. Chem. Theory Comput., 1 (2005) 1133-1152. 

The last case concerns the solvent molecules with large dielectric constants or strong basicity the ions can be rapidly solvated (in the bulk or in large clusters) and proton transfer occurs. Since the emission arises from the transferred state, the Stokes shift is important (typically around 9000 cm"1 with a large bandwidth). The 1-naphtholate fluorescence in neutral water or a mixture of polar solvents... 

Born-Oppenheimer molecular dynamics simulations for neutral and ionized phenol-water clusters are reported. The results for [C6H50D-(H20)4],+ illustrate how the PT dynamics is coupled to fluctuations of the solvent. The kinetics of PT/recombination in [C6H50D-(H20)4] + clusters is related to strong fluctuations of the electrostatic field of the water molecules and this relationship points out the relevance of investigating the electronic properties of the HB network for understanding chemical reaction in solution. 

The scope of this paper is to provide an overview of methods used to study properties of electrically neutral molecular clusters initiating particle formation in the troposphere, with focus on quantum chemistry. The review of results is intended to be complete with regard to water-sulfuric acid-ammonia clusters. Concerning studies on clusters including other molecular species, we review representative examples and newest publications. Ionic clusters and clusters involving iodine, related to coastal nucleation, are mentioned in passing. 

TABLE 7.23 Relative Energy (in kcal mol ) of the Water Clusters of Glycine Zwitterion Minus the Neutral Tautomer... 

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