This Thesis is concerned with the prediction, synthesis, characterization and testing of inorganic materials for Second Harmonic Generation (SHG). Chapter One describes the fundamentals of non-linear optics, and poses the problems, and some of their solutions which confront the synthetic chemist and the theoretical prediction of the second order hyperpolarizability constant β using CNDOVSB calculations. Chapter Two describes the design, implementation and calibration of an apparatus for measurements of the second harmonic generating efficiency of solids based on the Kurtz powder technique, and a solvatochromic method for the determination of β. Novel compounds with potential chirality due to atropisomerism, asymmetric octahedral structures, and asymmetric tetrahedral symmetry of metal centers are discussed in Chapters Three to Five. Chapter Three surveys the use of pentane-2,4-dionato- ligands and their coordination compounds as possible NLO active materials. The single crystal X-ray structures of bis(triphenylphosphine)(4-nitrobenzoylacetonato)palladium(II) tetrafluoroborate and tris(triphenylphosphine)[3-(2,4-dinitrophenyl)-pentane-2,4-dionato]palladium(II) tetrafluoroborate were determined. Chapter Four describes the syntheses, characterization and SHG properties of trans-β-ionylidenecyanoacetic acid (2-cyano-3-methyl-5-(2,6,6-trimethyl-l-cyclohexen-1- yl)-2,4-pentadienoic acid) and some of its metal and non-metal salts. Chapter Five describes the synthesis, characterization and second harmonic generation properties of some platinum(II) and palladium(II) complexes of β- ionylidenecyanoacetic acid. Chapter Six describes the use of conventional asymmetric carbon centers to introduce chirality into centrosymmetric compounds. The chiral compound (L)-N-[2-cyano- 3-methyl-5-(2,6,6-trimethyl-1 -cyclohexene-1 -yl)-2,4-pentadiene-1 -one]-L-proline and some of its salts were synthesized from β-ionylidenecyanoaeetic acid and tested for SHG.

This Thesis describes the synthesis, structural characterization and properties of some tin(II) and tin(IV) compounds containing bidentate ligands. Chapter 1 describes the main spectroscopic techniques used in the identification of tin(II) compounds; infra-red, ¹¹⁹Sn Mössbauer and n.m.r spectroscopy are outlined, and relevant examples given. A comprehensive listing is given of the main spectroscopic and structural properties of known tin(]3) compounds. Chapter 2 describes the general synthetic methods employed for the formation of tin(II)-oxygen heterocyclic compounds. A range of catecholate and related complexes of tin(II) were synthesized and the role of the substituent investigated with regard to their physical properties, especially their solubilities. The use of 4-nitrocatechol leads to a soluble product, {Sn[O-4-NO₂-C₆H₃O][OC₄H₈]}>sub>n</sub>, which enabled it to be studied spectroscopically and its solid state structure to be determined. The nature of the bonding in {Sn[O-4-NO₂-C₆H₃O][OC₄H₈]}_n was investigated using Extended Hiickel molecular orbital calculations. Chapter 3 describes the chemical reactivity of the novel, soluble, tin(II)-oxygen heterocycle {Sn[O-4-NO₂-C₆H₃O][OC₄H₈]}_n. Reaction with iodine gives SnI₂ [O-4-NO₂-C₆H₃O][OC₄H₈]<sub>2<sub>. Reaction with the Lewis base such as 1,2-diaminopropane gives Sn[NH₂CH₂CH(Me)H₂N][O-4-NO₂-C₆H₃O][OC₄H₈], whilst benzyltriethylammonium chloride gives {[Et₃BzN][SnCl(O-4-NO₂-C₆H₃O)]}_n. The solid-state structure of the compound consists of polymeric chains of [SnCl(O-4-NO₂-C₆H₃O)]^- and associated [Et₃BzN]⁺ cations. Reaction with BF₃.Et₂O gives the adduct F₃B.Sn[O-4-NO₂- C₆H₃O][OC₄H₈]. Reaction with W(CO)<sub>5_{thf gives {(OC)₃W.Sn[(O-4-NO₂- C₆H₃O)(OC₄H₈)]}₂ in which the tungsten atoms are believed to be bound η⁶ to the aromatic rings. Reaction with bis(triphenylphosphine)platinum-ethylene or tris(triphenylphosphine)platinum gives {PtH[PPh₃]₃}{[μ₂-O][μ₂-OH][Sn(O-4-NO₂- C₆H₃O)]₂}, the anion containing tin(II) and tin(IV) centres. Reaction with RhCl[CNC₈H₉]₃ gives {RhCl[CNC₈H₉]₃[μ₂-Sn(O-4-NO₂-C₆H₃O)]}₂. Reaction with Ph₃PAuCl gives the cluster Au₄(PPh₃)₄(μ₂-SnCl₃)₂, which is the first known example of a compound containing a μ₂-SnX₃ fragment. In comparison with SnCl₂, {Sn[O-4-NO₂- C₆H₃O][OC₄H₈]}_n only weakly inserts into the platinum-chlorine bonds of PtCl₂(dppe). Two molar equivalents of SnCl₂ reacts with PtCl₂(dppe) to give Pt(dppe)(SnCl₃)₂. Addition of a further equivalent of SnCl₂ in the presence of tetraethylammonium chloride gives [Et₄N][Pt(dppe)(SnCl₃)₃]. The platinum centre in this ion has a distorted trigonal bipyramidal geometry. Chapter 4 describes the synthesis of a number of tin(II)-sulphur heterocycles. The reaction between Sn[SC₆H₄S] and TMEDA gives a soluble adduct, Sn[SC₆H₄S]TMEDA. A number of tin(II)-nitogen heterocycles were also synthesized. Their intense colours and their instability towards air oxidation indicated that they were monomeric in the solid-state. Chapter 5 outlines the basis for non-linear optical properties, especially their SHG effects. A wide range of tris(catecholato)tin(IV) compounds were synthesized and tested for SHG activity. A number were found to have a significant SHG effect, especially [(O-4- NO,sub>2}-C₆H₃O)₃Sn][NHEt₃]₂, which has an SHG effect 1.33 x urea.

Thesis (M.Sc.(Chemistry))--University of Pretoria, 2003. / Summaries in Afrikaans and English. Includes bibliographical references.

Com o objetivo de verificar o consumo alimentar e o estado nutricional em relação ao zinco de crianças submetidas a um programa de suplementação com ferro, foram estudadas 150 crianças com idade entre 2 e 7 anos, que pertenciam a por 2 creches do município de São Paulo. O período de estudo foi de 7 meses, dividido em três fases (F0, F1 e F2); onde avaliou-se em cada fase a dieta oferecida e a concentração de zinco no eritrócito das crianças. Na fase inicial do estudo (F0) avaliou-se a dieta normal oferecidas nas creches e o estado nutricional inicial das crianças; na F1, a creche ST recebeu o alimento fortificado com ferro e a creche SM recebeu o mesmo alimento porém sem a fortificação. Já na F2, a creche ST recebeu o alimento sem fortificação e a SM o alimento fortificado. Pelos resultados obtidos pode-se concluir que: as dietas se apresentaram deficientes em caloria e zinco para a creche ST e também em ferro para a creche SM, não estando adequada especialmente para as crianças acima de 4 anos; a fortificação do queijo \"petit suisse\" com ferro aminoquelato não causou mudança na concentração de zinco nos eritrócitos das crianças analisadas ao longo do estudo, embora o estado nutricional das mesmas em relação a este mineral encontrava-se deficiente podendo ser atribuido à qualidade da dieta. / Aiming to value the food consumption and the nutritional status of zinc on infants submitted to an iron supplementation program, were studied 150 pre-schollars aged 2 to 7 years old of two nurseries (ST e SM) in the city of São Paulo. Studies were seven month, based on three stages (F0, F1 e F2), where was assessed the diets offered and the erythrocite zinc on infants, in the each stage. In the initial stage (F0), were assessed the regular diets offered by the nurseries and the initial nutritional status on infants; in the F1), the diets from nursery ST had meals supplemented with iron and the diets from nursery SM had the same meals although without the supplementation. In F2), the diets from nursery ST had meals without the supplementation and the diets from nursery SM the meals supplemented with iron. According with the results we can conclude: the diets were calories and zinc deficient to nursery ST and iron defícient to nursery SM, also; the iron supplementation in the \"petit suisse\" cheese with aminoquell iron did not cause any change in the erythrocite zinc concentration of the children being studied although the nutritional status were zinc deficient due to a quality of the diets.

This thesis reports the theoretical investigations aimed at understanding the structure, stability and properties of a few inorganic compounds. The first chapter presents an introductory overview of the theories used to solve the questions addressed in the thesis. A brief discussion of the work is also presented here. The second chapter deals with electron reservoirs which have been one of the basic motifs of single-electron device. Mononuclear vinylidene complexes of type Mn(C5H4R’)(R” 2 PCH2CH2PR "2)= C = C(R1)(H) were synthesized and reported [Venkatesan et al, Organometallics 25, 5190 (2006)] as potential electron reservoirs capable of storing and releasing electrons in a reversible fashion. These compounds have been of great interest because their red-ox chemistry (reversible oxidative coupling and reductive decoupling) is governed by the C - C bond. However slow oxidation of the mononuclear vinylidene complexes leads to undesired product. In our model compound Mn(C5H5)(PH3)2 = C = C(R1)(H), we substituted the cyclopentadienyl moiety by isolobal dianionic dicarbollyl ligand Dcab2- (C2B9H2-11 ). This simple substitution could reduce the production of undesired product. Calculations of vertical detachment energy, thermodynamic feasibility and molecular orbital analysis showed that this substitution was thermodynamically feasible and led to easy oxidation and dimerization of the parent compound accompanied with better reversibility of the reaction. The effect of substituents (R = H,Me,Ph) on Cβ atom of our model system was also analyzed. The substituent on β carbon had a great effect on the stability and reactivity of these complexes. Our comparative study between Mn(C5H5)(PH3)2 = C = C(R)(H) and Mn(Dcab)(PH3)2 = C = C(R)(H)−1 (where R = H,Me,Ph) predicted the latter to be a more potential electronic reservoir. Gas-phase observations on MAl 4- (M = Li, Na, Cu) and Li3Al-4 coupled with computations led to the conclusion that Al42− [Boldyrev and Wang et al, Science 291, 859 (2001)] is “aromatic” while Al44- is “antiaromatic” [Boldyrev and Wang et al, Science 300, 522 (2003)]. It has been reported by Pati et al [J. Am. Chem. Soc. 125, 3496 (2005)] that co-ordination with a transition metal can stabilize the “antiaromatic” Al4Li4. In the first section of chapter three, it has been reported that Al4Li4 can also be stabilized by capping it with main group element like C and its isoelectronic species BH. Calculations of binding energy, nuclear independent chemical shift (NICS), energy decomposition analysis and molecular orbital analysis supported the capping induced stability, reduction of bond length alternation and increase of aromaticity of these BH/C capped Al4Li4 systems. The interaction between px and py orbitals of BH/C and the HOMO and LUMO of Al4Li4 was responsible for such stabilization. Calculations suggested that capping might introduce fluxionality in the molecule at room temperature. Al has valence electronic configuration of s2p1 and Al42− has been shown to have multiple aromaticity [Boldyrev and Wang et al, Science 291, 859 (2001)]. Analogy between electronic configuration s2pof Al and d1sof Sc/Y prompted us to explore the aromaticity of M42− clusters (M = Sc, Y ) which have been described in the second section of chapter three. Different geometries of M42− clusters (M = Sc, Y ) were explored, and the planar butterfly-like D2h geometry (two fused triangles) was found to be the most stable isomer. This is unlike the case of Al42− where D4h isomer was the most stable one as reported in the literature. In D2h geometry of M42− clusters (M = Sc, Y ), significant electron delocalization in each wing of the butterfly indicated fused d aromaticity. Atomization energy and chemical hardness supported the preference of D2h geometry over the D4h geometry. Molecular orbital analysis showed that the d-electrons were delocalized in each triangle of D2h geometry. Our interest in the search of new kinds of binuclear sandwich compounds led us to consider sandwiched metal dimers CB5H6M - MCB5H6 (M = Si, Ge, Sn) which are at the minima in the potential energy hypersurface with a characteristic M - M single bond. This work has been described in the first section of chapter four. The NBO analysis and the M - M distances ( ˚A) (2.3, 2.44 and 2.81 for M= Si, Ge, Sn respectively) indicated substantial M - M bonding. Consecutive substitution of two boron atoms in B7H7−2 by M (Si, Ge, Sn) and carbon respectively led to neutral MCB5H7, where M - H bond bent towards the carbon side of the five membered ring. Dehydrogenation of two MCB5H7 might lead to our desired CB5H6M - MCB5H6 where similar bending of M -M bond has been observed. The bending of M - M bond in CB5H6M -MCB5H6 was more than the M - H bending in MCB5H7. Molecular orbital analysis has been done to understand the bending. Larger M - M bending observed in CB5H6M - MCB5H6 in comparison to M - H bending observed in MCB5H7 was suspected to be favored by stabilization of one of the M - M π bonding MO’s. Preference of M to occupy the apex of pentagonal skeleton of MCB5H7 over its icosahedral analogue MCB10H11 has been observed. Structures of sandwiched binuclear L- M – M - L where M = Ti, Zr and L = Cp, C3B3H6 were also investigated as described in second section of chapter four. We found that these compounds having bent geometry with short M - M distance (1.87˚A for M=Ti and 2.29˚A for M=Zr) lie at the minima in the potential energy hypersurface. Bending from the linear geometry led to the stabilization of M - L antibonding interaction in L - M – M - L. Molecular orbital analysis, NBO calculations, Wiberg bond index and charge analysis suggested M2+ unit to be embedded in between two L’s in L - M – M - L. Molecules that have the ability to perform interesting mechanical motions have always been of great interest. Umbrella inversion of ammonia is one of the most interesting and well studied phenomena. This study has led to the development of the MASER. The possibility of inversion of the molecule C9H9−Li+ by the movement of Li+ through the C9H9−ring was studied earlier [Das et al, Chem. Phys. Lett. 365, 320 (2002)]. In the fifth chapter theoretical investigation on a B12 cluster has been reported, which could exhibit a through ring umbrella inversion. Calculations showed that a part of the molecule, consisting of a three membered boron ring could invert through the rest, viz., a nine membered boron ring. Using a simple model, the double well potential for the motion was calculated. The barrier for inversion was found to be 4.31 kcal/mol. The vibrational levels and tunneling splitting were calculated using this potential. It was found that the vibrational excitation to the v = 17 level caused large amplitude “inversion oscillation” of the molecule. After considering the tunneling effect, inversion rate at 298K was calculated by using transition state theory and was found to be 1.17 x 1010/s. Finally, in the last chapter the main results of the thesis have been summarized.

published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

No description available.

No description available.

The organic linker 1,2,4,5-benzenetetracarboxylic acid (BTC) has been widely used in the construction of lanthanide metal-organic frameworks (MOFs) due the high symmetry and versatile nature of its structure. Under identical hydrothermal reaction conditions, it was discovered that lanthanide BTC MOFs will form one of four unique structures based on its location in the series (La-Sm, Eu-Tb, Dy-Tm, Yb-Lu). This is uncommon in LOF materials, as in many cases the same compound can be produced for all of the lanthanides or two different structures may be observed for the first and second half of the series. Descriptions and comparisons of these structures as discussed herein, noticeably the decrease in coordination number and the lanthanide-oxygen bond lengths as the lanthanide atomic number increases. This thesis also attempts to use these compounds to catalyze a model mixed-aldol reaction. Two closely related BTC compounds from yttrium and uranium are also presented. The structure of the yttrium BTC MOFs was identical to that of the Eu, Gd and Tb compounds. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2015. / FAU Electronic Theses and Dissertations Collection

Thesis (Ph. D.)--State University of New York at Binghamton, Department of Chemistry, 2006. / Includes bibliographical references.