China
Africa
Explore chapters and articles related to this topic
Polymeric Second-Order Nonlinear Optical Materials and Devices
Published in Sam-Shajing Sun, Larry R. Dalton, Introduction to Organic Electronic and Optoelectronic Materials and Devices, 2016
Various crystal-engineering [1] strategies have been reported to tailor molecules into noncen-trosymmetric arrangements via multiple noncovalent intermolecular interactions such as hydrogen bonds, metal–organic coordinations, and van der Waals interactions. The design and synthesis of a chromophore with large hyperpolarizability and extended π-conjugations, which crystallize into an acentric space group is a daunting challenge since we do not know how to calculate solid-state structures of molecules with some degree of chemical and conformational complexities yet. Although the introduction of a chiral auxiliary group to an NLO chromophore should produce acentric molecular packing in the solid state, the chirality alone does not show efficient NLO responses in crystals. The electrostatic dipole–dipole interactions between molecules with large dipole moments can form partially antiparallel packing resulting in small macroscopic dipole moment in polar direction of acentric crystals [2]. Moreover, introduction of bulky substituents or chiral auxiliary groups to a chromophore can significantly decrease the active molecular fractions and thermal stabilities of crystals.
Other Modification Processes
Published in Dick Sandberg, Andreja Kutnar, Olov Karlsson, Dennis Jones, Wood Modification Technologies, 2021
Dick Sandberg, Andreja Kutnar, Olov Karlsson, Dennis Jones
The use of concentrated electrolytic solutions has been reported to be an efficient way of introducing metal salts into polymeric systems (Merk et al., 2017), and this method has been used to deposit barium sulfate into the cell lumen and secondary walls. The location and structure of the salt deposit were determined using a combination of scanning electron microscopy, Raman mapping and scanning micro-focused wide-angle X-ray scattering. They growth appeared to progress from the mineralised cell walls towards the lumen centre via dendritic crystals. This method could lead to templated crystal engineering and the design of new bio-inspired materials.
Exploring the coordination chemistry of a low symmetry, bent dipyridyl ligand
Published in Journal of Coordination Chemistry, 2022
Nicholas Kyratzis, David R. Turner
Crystal engineering has been a fundamental part of the design and formation of coordination polymers and MOFs over the last 20 years [1, 2]. The process of forming metal-organic frameworks inherently relies upon the crystallization process and the supramolecular interactions that can form, even in amorphous MOFs in which the long-range crystalline order is lacking [2]. Understanding the reasoning of how coordination polymers are formed using different coordinating groups, or different functionalities within the non-coordinating regions of the ligand, can help form more robust and predictable systems. Coordination polymers and metal-organic frameworks are often evangelized for their potential applications including catalysis [3–5], gas storage [6–8], and separations [9–12]. However, key to this field still remains the ability to control the design of these materials [13, 14].
Syntheses and structure characterization of seven inorganic-organic hybrids based on N-Brønsted bases and perhalometallates
Published in Inorganic and Nano-Metal Chemistry, 2021
Zhihang Li, Kaikai Hu, Weiqiang Xu, Shouwen Jin, Liqun Bai, Daqi Wang
One of the principal challenges of modern chemistry is that of the crystal engineering of new crystal structures. The ambition of this branch of crystal engineering is to design and prepare novel crystal structures based on molecular building blocks.[1–3] This is a considerable challenge given the immense difficulties of predicting a crystal structure from knowledge of its molecular components. A widely used approach is to exploit the principles of supramolecular chemistry to achieve desired modes of aggregation by well-known synthons.[4,5] Chemists have employed this strategy to create novel structures based on metal complex anions that accept H-bonds and organic cations with H-bond donor capability.[6–11] For this, much attention has been put on organic-inorganic hybrids from metal-halide anions.[12–15] The most typical cations in hybrid crystals were alkylammonium/aromatic ammonium.[16]
Review: Recent advances of one-dimensional coordination polymers as catalysts
Published in Journal of Coordination Chemistry, 2018
Edward Loukopoulos, George E. Kostakis
While the term “coordination polymer” has been regularly used in scientific reports since the 1950s [3], interest in this field exploded in the early 1990s (Chart 1) when Hoskins, Robson and others published a series of papers [4–9] proposing a design approach toward CPs with targeted structures. The development of this concept was further aided by the rising growth of crystal engineering, which concerns the study and understanding of intermolecular interactions (e.g. hydrogen bonds, halogen bonds, π⋯π interactions, etc.) in a crystal structure, toward the design of new molecules with desired applications [10–12]. These concepts have been widely used for production of CPs ever since [13]: synthetic variables such as metal salt [14, 15] and ligand selection [16–18], or solvent [19–22] and temperature [23–25] conditions may be controlled and manipulated to afford polymeric compounds with the desired shape and dimensionality, and most importantly the desired applications. As a result, a large number of CPs has been reported with potential properties in anion exchange [26, 27], crystal-to-crystal transformation [28–31], gas sorption [32, 33], drug delivery [34, 35], luminescence [36, 37], magnetism [38], sensing [39, 40], and catalysis [41].