New bis-pyrazole-bis-acetate based coordination complexes: influence of counter-anions and metal ions on the supramolecular structures

A new flexible bis-pyrazol-bis-acetate ligand, diethyl 2,2’-(pyridine-2,6-diylbis (5-methyl-1H-pyrazole-3,1-diyl))diacetate (L), has been synthesised, and three coordination complexes, namely, [Zn(L)2](BF4)2 (1), [MnLCl2] (2) and [CdLCl2] (3) have been obtained. All ligands and complexes were characterised by IR, mass spectroscopy, thermogravimetric analysis and single-crystal X-ray diffraction. Single crystal X-ray diffraction experiment revealed that the primary supramolecular building block of 1 is a hexagonal chair shaped 0D hydrogen bonded synthon (stabilised by C–H∙∙∙O hydrogen bonding and C=O∙∙∙π interactions), which further built into a 2D corrugated sheet-like architecture having a 3-c net honeycomb topology, and finally extended to a 3D hydrogen bonded network structure having a five nodal 1,3,3,3,7-c net, through C–H∙∙∙F interactions. On the other hand, the two crystallographically independent molecules of 2 exhibited two distinct supramolecular structures such as 2D hydrogen bonded sheet structure and 1D zigzag hydrogen bonded chain, sustained by C–H∙O and C–H∙∙∙Cl interactions, which are further self-assembled into a 3,4-c network structure, and 3 showed a 2D hydrogen bonded sheet structure. The supramolecular structural diversity in these complexes is due to the different conformations adopted by the ligands, which are mainly induced by different metal ions with coordination environments controlled by different anions. Hirshfeld surface analysis was explored for the qualitative and quantitative analysis of the supramolecular interactions

DIMERIC MOLECULAR AGGREGATION MOTIF IN CRYSTAL OF 2,7-DIETHOXY-1-(4-NITROBENZOYL)NAPHTHALENE: CORRELATION OF SINGLE MOLECULAR STRUCTURE, MOLECULAR ACCUMULATION STRUCTURE AND NON-COVALENT-BONDING INTERACTIONS

Crystal structure of 2,7-diethoxy-1-(4-nitrobenzoyl)naphthalene, C21H19NO5, is reported and discussed on the characteristics of the spatial organization of single molecule and molecular aggregation as contrasted with a homologous compound. The molecular structures of these compounds differ only in the kind of alkoxy group of 2,7-positions of naphthalene rings, i.e., ethoxy groups for title compound and methoxy ones for homologue. In single molecular crystal structure, the 4-nitrobenzoyl groups of these molecules are attached non-coplanarly to the naphthalene ring. The congested situation makes bonds connecting naphthalene ring and carbonyl group fixed to turn stereogenetic, which allow the independent existence of atrope stereoisomers of (R)- and (S)-enantiomeric conformer molecules, contrary to their solute state where the fast interconversion disturbs the distinction of the enantiomeric molecules. The two pairs of the enantiomeric molecules are related by two-fold helical axis in the asymmetric unit of P21/n space group for title compound and P21/c for homologous compound, exhibiting the number of molecules (Z) is four for both compounds. In crystal of title compound, (R)- and (S)-enantiomers are connected to each other by pi…pi stacking interaction and two types of C–H…O=N non-classical hydrogen bonds, (sp2)C–H…O=N and (sp3)C–H…O=N non-classical hydrogen bonds along b-axis, forming centrosymmetric dimeric molecular aggregates. The dimeric units are stacked into columnar structure by (sp2)C–H…O=C non-classical hydrogen bonds between molecular unit of identical enantiomeric configuration along a-axis. The columns are also connected by (sp2)C–H…OEt non-classical hydrogen bonds between molecular unit of identical enantiomeric configuration along c-axis to give sheet-like aggregate composed of molecules of same enantiomeric configuration spreading on ac-plane. The sheets are piled up through (sp3)C–H…pi non-classical hydrogen bonds between opposite enantiomeric molecular units of next dimeric aggregates along b-axis. In crystal of the homologous compound, 2,7-dimethoxy-1-(4-nitrobenzoyl)naphthalene, centrosymmetric dimeric aggregate resulted from the association of (R)- and (S)-enantiomers via pi…pi stacking interactions are also observed. The centrosymmetric dimeric aggregates are unidirectionally lined by two kinds of non-classical hydrogen bonds between molecular unit of identical enantiomeric configuration, (sp3)C–H…O=C and (sp3)C–H…pi non-classical hydrogen bonds, giving columnar structure. The columns are accumulated giving a wavy sheet structure composed of stripes of respective enantiomeric configuration oriented alternatively and anti-parallelly through weak (sp2)C–H…pi non-classical hydrogen bonds. The difference of higher ordered structure between title compound and homologue is plausibly explained according to one CH2 margin in 2,7-dialkoxy groups, i.e., elongation of the least length in alkyl group of title compound compared to homologue brings about the sterically significant hindrance among dimeric aggregates that makes rather anisotropic intermolecular non-covalent bonding interactions resulting in accumulating sheet structure. For 1-monoaroylnaphthalene compounds, the most stabilized single molecular structure on condition that the sufficiently effective intermolecular interaction is absent is proposed the perpendicular alignment of naphthalene and benzene rings to prevent the steric repulsion of two aromatic rings. The smaller spatial volume of methyl group in homologue molecule is plausibly able to be merged without large alternation in the single molecular structure most stabilized. Contrarily, the additional methylene unit at 2,7-alkoxy group probably requires the rather large perturbation from the supposed structure most stabilized

New Liquid Crystalline [2]Rotaxanes

This thesis presents design, synthesis and characterization of a range of new liquid crystalline interlocked molecules and to study structure-property relationships between rotaxane design and mesomorphism. Chapter 1 introduces concepts of supramolecular chemistry and liquid crystals and cooperative effect between [2]rotaxane and liquid crystals towards functional molecular machines. In Chapter 2, a systematic approach to introduce liquid crystallinity into the 1,2-bis(pyridinium)ethane/DB24C8 motif is described. The chapter begins with synthesis and purification of dumbbells (without macrocycle) and [2]rotaxanes (with macrocycle) substituted with purely aliphatic extended 3,5-disubstituted stoppers with increasing alkyl chain length. Chapter continues with phase characterization and structure-property relationships between dumbbells and rotaxanes. The dodecane chain was sufficiently fluid to induce smectic mesomorphism in both the dumbbell and [2]rotaxane, with [2]rotaxane forming SmA phase by POM and XRD analysis. Chapter 3 presents an extension to Chapter 2 with the addition of longer straight chain and branching aliphatic chains to our 1,2-bis(pyridinium)ethane/DB24C8 rotaxane motif to study structure-property relationships and phase characteristics. The ability of the side-chain to self-organized showed large differences in phase behaviour. The pentadecane straight chain extended [2]rotaxane exhibited a unidentified mesophase, the hexadecane straight chain [2]rotaxane showed SmA mesomorphism, the branched hexadecane and the hyperbranched [2]rotaxanes both showed lamellar soft crystal phases. Chapter 4 describes the effect of applying groups typical for low molecular weight LCs (siloxanes) to our 1,2-bis(pyridinium)ethane/DB24C8 motif and a modified rotaxane design based on a bis(oxymethylbenzylpyridinium)ethane/DB24C8 motif. The structure-property relations between both systems, and in comparison with the dodecane chain substituted systems, are presented. The new design revealed SmC mesophases for both the dodecane and siloxane substituted [2]rotaxanes. Chapter 5 focuses on the introduction of chirality into the siloxane substituted [2]rotaxane with SmC mesomorphism presented in Chapter 4. Chirality was introduced via a chiral anion as well as incorporation of a chiral crown. Observations to changes in the superstructure from the incorporation of chirality is addressed. The chiral anion exchanged [2]rotaxane showed SmC* mesomorphism and the chiral crown [2]rotaxane showed SmX* mesomorphism. Chapter 6 presents the design and synthesis of a molecular shuttle based upon the structure-property relations determined from the previous chapters

Conjugated Macrocycles in Organic Electronics

The discipline of organic electronics encompasses the design and synthesis of molecules for use in organic field effect transistors, organic photovoltaics, organic photodetectors, single molecule electronics, sensors, and many more. The rationale for studying organic electronic materials is compelling: organics have the potential to be low cost, processable, and flexible complements to silicon technologies to combat some of the most pressing environmental issues. Organic molecules that transport carriers are used as the active layer in many device applications. Molecules that possess energy levels that allow for electron or hole transport are typically π-conjugated materials. There has been swift progress on the design and synthesis of π-conjugated materials that possess a large density of high energy electrons such as acenes. Yet there has been less growth on materials with low energy vacant orbitals to accept an electron. Fullerenes are the ubiquitous acceptor materials used in organic electronics. Over the past few years, there have been several groups, including our own, that have synthesized non-fullerene materials for use in organic field effect transistors and solar cells. In particular, the Nuckolls laboratory has pioneered the design and synthesis of a class of molecules called contorted aromatics and studied these molecules in range of organic electronic applications. Conjugated macrocycles are one sub-class of the contorted aromatic family. This Thesis describes a body of research on the design, synthesis, and application of a new class of electronic materials made from conjugated macrocycles. Each of the macrocycles comprises perylenediimide cores wound together with various electronic linkers. The perylenediimide building block endows each macrocycle with the ability to transport electrons, while the synthetic flexibility to install different linkers allows us to create macrocycles with different electronic and physical properties. We use these materials in organic photovoltaics, field effect transistors, sensors, and photodetectors. The macrocycles possess vivid colors, absorb in the visible range of the solar spectrum, and are an exemplary class of materials to study how rigidity and strain affect device performance. We find that the strained and rigid macrocyclic framework affords each macrocycle with the ability to absorb lower energy visible light with respect to acyclic counterparts and the macrocycles outperform in photovoltaic applications. Rigidity was an important concept in our organic photodetector study: we found rigidity was one of the reasons our macrocycles outperformed both fullerenes and acyclic controls. The macrocycles all possess intramolecular cavities, and our recent studies focused on using this nanospace for sensing applications. Each of the studies described in this Thesis will demonstrate how macrocyclization is a design technique to enhance organic electronic performance

Covalent and Supramolecular Helical Polymers: The Dawn of Matryoshka Materials

Esta tese titulada: Polímeros Helicoidais Supramoleculares e Covalentes: o Albor dos Materiais Matrioshka, inclúe cinco proxectos de investigación nos que se abordarán o estudo das estruturas e o comportamento de polímeros helicoidais tanto supramoleculares coma covalentes. Finalmente a información recadada nestas pescudas será combinada, xerando así un novo material no que os dous motivos estruturais covalente e supramolecular estean presentes. A continuación expoñeranse os resultados máis relevantes de cada capítulo

Functional complex plasmonics : understanding and realizing chiral and active plasmonic systems

The present thesis concerns itself with the theoretical study and experimental realization of complex plasmonic systems for highly integrated nanophotonic devices and enhanced chiroptical spectroscopy. In particular, the two broad topics of active metasurfaces and chiral plasmonic systems are investigated to this end. In this context, the chalcogenide phase change material GeSbTe is utilized to demonstrate, for the first time, metasurface based beam steering and varifocal lensing devices. The versatility of this approach to lending active functionality to plasmonic systems is further evidenced through our realization of a chiral plasmonic system that both exhibits a wavelength tunable and handedness switchable chiroptical response. Furthermore, in order to enable a systematic study of plasmon- enhanced chiroptical spectroscopy, we rst establish and analyze canonical chiral plasmonic building blocks, in particular, the loop wire and chiral dimer structure. The results from this undertaking lead to fundamental insights for understanding complex chiral plas- monic systems. Finally, we implement chiral media in the commercial electromagnetic full- field solver Comsol Multiphysics to carry out rigorous numerical studies of the macroscopic electrodynamic processes involved in plasmon-enhanced circular dichroism spectroscopy revealing both substantial enhancement due to near-field effects as well as upper boundaries to the magnitude of such enhancements

等方相と共存するコレステリック液晶滴の熱-力学交差相関による剛体回転

早大学位記番号:新9169博士(理学)早稲田大