CHEM01200604005 A. K. Pathak - Homi Bhabha National Institute

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CHAPTER 2 Structure and Energetics of Water Embedded Anionic Clusters 2.1. Introduction Lately, hydrogen bonded water clusters encapsulating charged solutes have been a 1-3, 7-10,14-15,18- subject of intense research both by theoretical and experimental researchers. 19,23-35 . When a charged solute is added into a solvent water pool, preexisting hydrogen bonded water network in solvent breaks up to accommodate the solute and a new hydrogen bonded water network forms surrounding the solute. This process of hydration with an anionic solute is rather complex compared to that of a cationic species as cation binds strongly with the solvent water molecules. 1 A delicate balance between water-anion and water-water interactions determines the structure of hydrated cluster of the anion. Studies on finite size hydrated clusters are important because of the strong dependency of their properties on their size and structure and to understand the growth motif of solvent molecules surrounding the solute. Recently, with the advent of supersonic expansions and nozzle beam techniques as well as sophisticated theoretical techniques, solvation in small as well as large size hetero clusters has been amenable to experimental and theoretical observations. A number of experimental, theoritical and simulation studies have been carried out to understand the structural, energetics, spectroscopic and dynamic aspects of hydration at molecular level on small negatively charged ions. 7-10,14-15,18-19,23-35 Among the simplest of the anionic systems studied by experimental and theoretical techniques is the 18
hydrated halide series, X¯.nH 2 O, (X=Cl, Br, I). 7-8,14 Beyond these simple halide anions, the next complex hydrated clusters investigated involve diatomic singly charged anions of the type Y − .nH 2 O, where Y refers to OH, 8,15 O 2 , 23 NO 25 . •− In this chapter, both open shell systems like, halogen dimer radical anions, X 2 (Cl 2 •− , Br 2 •− & I 2 •− ), carbonate radical anion (CO 3 •− ) and close shell systems like, carbonate anion (CO 2− − 3 ), nitrate anion (NO 3 ) are taken to understand the process of microhydration. The study on the evolution of hydration motifs when a second halogen atom, X • is added to X − to form X •− 2 (Cl •− 2 , Br •− 2 & I •− 2 ) diatomic species should provide information on binary ion-molecule interaction with extended electron distribution. Study on CO • 3 ⎯ radical anion is also a subject of numerous investigations not only due to its role as terminal ion in atmospheric chemistry but also due to its rich and varied photophysical properties. Interest in oxidative chemistry of carbonate radical anion, CO • 3 ⎯ has significantly grown within the last decade due to its important role in inflammatory processes. It is also reported that carbonate radical anion is produced in the physiological system during xanthine oxidase turnover. Xanthine oxidase is generally recognized as the key enzyme in purine catabolism. 39 Such study will help to enhance our understanding on molecular level interactions between solvent water molecules and negatively charged ions in aqueous solution. Investigations on hydrated clusters of these radical anions are also useful to radiation chemistry studies in water medium. In aqueous solution, hydroxyl radical ( • OH) reacts with X¯ (X=Cl, Br & I) to form a transient species, which has a strong optical absorption in the visible region. This absorption maxima is assigned to the halogen dimer radical anion species, X 2•¯( X=Cl, Br & I), a specific one electron oxidation species. Similarly in aqueous solution, hydroxyl radical ( • OH) reacts with 19
Page 1 and 2: MICROSOLVATION OF CHARGED AND NEUTR
Page 3 and 4: STATEMENT BY AUTHOR This dissertati
Page 5 and 6: Dedicated to my Daughter, Wife and
Page 7 and 8: CONTENTS Page No. SYNOPSIS LIST OF
Page 9 and 10: CHAPTER 4 Solubility of Halogen Gas
Page 11 and 12: 7.3.4. IR and Raman Spectra 117-121
Page 13 and 14: S Macroscopic Microscopic Dual leve
Page 15 and 16: molecular level interaction during
Page 17 and 18: Chapter 3: This chapter describes I
Page 19 and 20: In this system the conformers of a
Page 21 and 22: LIST OF FIGURES Page No. Fig. 1.1 2
Page 23 and 24: Fig. 2.6 54 (I) Plot of calculated
Page 25 and 26: (IIIA) Cl 2 .3H 2 O; (IIIB) Br 2 .3
Page 27 and 28: Fig. 6.3 104-105 Calculated scaled
Page 29 and 30: LIST OF TABLES Page No. Table. 2.1
Page 31 and 32: CHAPTER 1 Introduction 1.1. Microso
Page 33 and 34: 1.2. Motivation 1.2.1. Macrosolvati
Page 35 and 36: ulk water and pure neutral water cl
Page 37 and 38: insight about the electronic struct
Page 39 and 40: Newton -Raphson (NR) method expand
Page 41 and 42: potential energy surface for these
Page 43 and 44: terms, the energy can be written in
Page 45 and 46: Boyd proposed the use of Gaussian t
Page 47: eported experimental findings. Theo
Page 51 and 52: anions (Cl •− 2 , Br •− 2 &
Page 53 and 54: geometrical parameters close to MP2
Page 55 and 56: symmetrical DHB, SHB or WHB arrange
Page 57 and 58: of I-I axis and having the least I-
Page 59 and 60: Br •− 2 .nH 2 O hydrated cluste
Page 61 and 62: VI-F VI-G VII-A VII-B VII-C VII-D V
Page 63 and 64: To see the effect of hydration on t
Page 65 and 66: Five minimum energy structures disp
Page 67 and 68: arrangements. In total, it has one
Page 69 and 70: NO 3 − .nH2 O (n ≥ 6), a few eq
Page 71 and 72: V-E V-F V-G V-H V-I VI-A VI-B VI-C
Page 73 and 74: VII-D VII-E VII-F VII-G VII-H VII-I
Page 75 and 76: VIII-K VIII-L Fig.2.2. Fully optimi
Page 77 and 78: clusters. Hydrated cluster having c
Page 79 and 80: However, these calculations do not
Page 81 and 82: Table 2.1. Weighted average energy
Page 83 and 84: Where, E[I •− 2 .nH 2 O] is the
Page 85 and 86: The variation of the weighted avera
Page 87 and 88: CHAPTER 3 IR Spectra of Water Embed
Page 89 and 90: ecome more meaningful. At present,
Page 91 and 92: I-A II-A II-B III-A III-B III-C III
Page 93 and 94: Cluster experiments are carried out
Page 95 and 96: 3350-3500 cm -1 (scaling factor ~0.
Page 97 and 98: these systems, X. nH 2 O (X= Br 2
Page 99 and 100:
CHAPTER 4 Solubility of Halogen Gas
Page 101 and 102:
including polarized and diffuse fun
Page 103 and 104:
and I 2 systems. The most stable st
Page 105 and 106:
Cl Cl Br Br I I VA VB VC Cl Cl Br B
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(Br δ+ -Br δ- ) in the studied hy
Page 109 and 110:
stabilization energy does not follo
Page 111 and 112:
80 Cl 2 .nH 2 O (n=1-8) 80 Br 2 .nH
Page 113 and 114:
separated ion pair in presence of s
Page 115 and 116:
adical ( • OH) reacts with HCO 3
Page 117 and 118:
most stable conformer for each size
Page 119 and 120:
The structures of the hydrated clus
Page 121 and 122:
Table 5.1. Calculated absorption ma
Page 123 and 124:
molar extinction coefficient value
Page 125 and 126:
ammonia. 61-62 Hydrogen bonded wate
Page 127 and 128:
stable minimum energy structure is
Page 129 and 130:
IV-A IV-B V-A V-B V-C VI-A VI-B VI-
Page 131 and 132:
6.3.3. Vertical Ionization Potentia
Page 133 and 134:
311++G(2d,2p) level, the scaling fa
Page 135 and 136:
K(NH 3 ) 4 K(NH 3 ) 5 IR Intensity
Page 137 and 138:
CHAPTER 7 Structure, Energetics and
Page 139 and 140:
Thus Monte Carlo based simulated an
Page 141 and 142:
I I I I I I I I A B C D I I I I I I
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interaction as well as solvent-solv
Page 145 and 146:
Table 7.1. Various energy parameter
Page 147 and 148:
change in VDE is observed. This is
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symmetric C-O stretching mode of CO
Page 151 and 152:
to the maximum charge transfer of t
Page 153 and 154:
CHAPTER 8 A Generalized Microscopic
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possible breakdown of these laws ma
Page 157 and 158:
P 7 P , , P , ,, 1 ∂ 2
Page 159 and 160:
M DE = (r, ω)C DE , (r,
Page 161 and 162:
known. However, for most of the com
Page 163 and 164:
The calculated bulk detachment ener
Page 165 and 166:
espect to experimentally measured v
Page 167 and 168:
References 1. Ohtaki, H.; Radani, T
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29. Turi, L.; Sheu, W.; Rossky,P.J.
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61. (a) Ehrler, O. T.; Neumark, D.
Page 173 and 174:
LIST OF PUBLICATIONS *1. “σ/σ
Page 175 and 176:
13. “Vibrational analysis of I
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CHEM01200604005 A. K. Pathak - Homi Bhabha National Institute

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