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Other Phases of Matter
Published in Mary Anne White, Physical Properties of Materials, 2018
Inclusion compounds are multicomponent materials in which one type of species forms a host in which other species reside. They can exist in solution or in the solid state. In the latter, the range of topologies of the host lattice allows several different types of structures, as shown in Figure 11.6. Inclusion compounds belong to the larger family of materials known as supramolecular materials; these are defined by properties that stem from assemblies of molecules. In the case of inclusion compounds, many physical and chemical properties are different in the supramolecular assembly than for the pure host or guest species. Supramolecular assemblies are generally held together by noncovalent forces such as hydrogen bonding, van der Waals interactions, and Coulombic forces. Industrial applications of inclusion compounds include fixation of volatile fragrances and drugs and inclusion of pesticides to make them safer to handle.
Supramolecular Assemblies of π-Electronic Charged Species
Published in Atsushi Nagai, Koji Takagi, Conjugated Objects, 2017
Yohei Haketa, Ryohei Yamakado, Hiromitsu Maeda
The formation of hierarchically well-defined supramolecular assemblies is currently of great interest in chemistry, biology, and materials sciences1. Because of the limitations in top-down processes for fabricating nanoscale fine materials that have precise arrangements of constituting molecules, the development of rational bottom-up processes is in high demand. Over the past decades, the principles of molecular assembly have been studied using molecules with diverse shapes and electronic states by studying their noncovalent intermolecular interactions such as hydrogen-bonding, metal coordination, van der Waals, π-π, dipoledipole, and electrostatic interactions. Suitable combinations of appropriate molecules through these noncovalent interactions enable the fabrication of structurally ordered states in both molecular and macroscopic levels. The alignment of molecules via specific interactions forms supramolecular assemblies with various nanoscale architectures (spheres, fibers, rings, vesicles, and tubes) and the resulting soft materials2 such as supramolecular gels, which are formed by trapping solvent molecules in the 3D networks of nanoscale objects3. Liquid crystals are soft materials with molecularly ordered assembled structures, which can be potentially used for transportations of electric charges, ionic species, and molecules4.
Dendrimers in Drug and Gene Delivery
Published in Ijeoma F. Uchegbu, Andreas G. Schätzlein, Polymers in Drug Delivery, 2006
Christine Dufes, Ijeoma F. Uchegbu, Andreas G. Schätzlein
When considering the general biocompatibility of dendrimer-based drug and gene delivery systems, one needs to be careful to distinguish between interactions and effects of the free dendrimer and those related to the delivery system as a whole, i.e., when the dendrimer is part of a supramolecular assembly. Dendrimers with suitable properties (i.e., appropriate hydrophile-lipophile balance (HLB), size, and topology) can self-assemble into higher-order structures, thus increasing their potential for use as drugs and gene carriers [49–51]. Self-assembling dendrimers with a variety of structures have been reported by several groups as recently described in Reference 52. Other supramolecular assemblies can be formed by interaction with other molecules, e.g., by complexation with drugs or DNA. The biological properties of such supramolecular structures may differ considerably from that of the free molecule. Although the complexation of a potentially toxic polymer can change its biological interaction profile and limit its toxicity, particulate materials may show distinct biodistribution or cellular trafficking characteristics, which can modify the toxicity profile.
Gelation properties of amino-acid-based bis-urea compounds in organic solvents and in the presence of surfactants
Published in Soft Materials, 2023
Kyra Danielle C. Magdato, Monissa C. Paderes
Recently, the self-assembly of systems with multiple components has gained much attention in supramolecular chemistry.[23–29] It enables the fabrication of complex supramolecular assemblies from simple building blocks via non-covalent interactions. This gives access to functional materials that are responsive to multiple external stimuli, resulting in high-end and more exciting applications. Supramolecular interpenetrating networks fabricated from the self-assembly of multicomponent systems have been reported in various systems including gelled liquid crystals[30–32] and microemulsions,[33] supramolecular functional complexes,[34,35] and low-molecular-weight gelators (LMWGs) in phospholipids[27] and micelle-forming surfactants.[36–38]
SiO2/Ni-GA nanoporous composite as an efficient adsorbent for the removal of cationic and anionic dyes
Published in Journal of Coordination Chemistry, 2023
Maryam Mohammadikish, Saleheh Salehi
Coordination polymers (CPs) are crystalline or amorphous materials prepared when organic linkers are connected to metal nodes through strong coordination bonds. These supramolecular assemblies often have unique properties, such as high surface area, mechanical, and thermal stabilities [12, 13]. They have received attention in a wide variety of applications, like separation, optics, molecular sensing, gas storage, photovoltaics, and catalysis [14–22]. In addition to crystalline macro-scaled metal-organic frameworks (MOFs), nano- and micro-scaled amorphous coordination polymers have been reported [23–25]. CPs have been extended as a new branch of colloidal compounds with excellent applications. In addition to the above benefits, there are several significant properties for CPs that improve their separation performance. Various parameters such as metal ions, unsaturated sites, functional groups, and organic linkers could supply interactions such as hydrogen bonds, electrostatic interaction, π-π interaction, and hydrophobic effects to increase selective adsorption [1, 26–28]. CPs as adsorbents have inherent defects such as aggregation, broad size distribution, and irregular morphology that limit their usage in separation methods. Combination of other solid compounds with CPs can remove their structural deficiencies and enhance utilization [29–31]. Thus, hybrid materials with high potential applications need more attention.
Crystal structures, proton conductivities and luminescence of two organic-inorganic hybrid materials based on Keggin-type clusters and Cu(II)/Cu(I)-bis(hydroxymethyl)-2,2′-bipyridine complexes
Published in Journal of Coordination Chemistry, 2021
Yan Zhao, Xianying Duan, Guangguang Zhang, Meilin Wei
Supramolecular assemblies are the self-assemblies of preselected molecular components as organic and/or inorganic molecular building blocks. They have been applied to many research fields, such as coordination chemistry, crystal engineering, and materials science in recent years [1–14]. Keggin-polyoxometalates [2, 4–9, 13, 14] and 4,4′-bis(hydroxymethyl)-2,2′-bipyridine (bhmbpy) [14b, 15], respectively, are important inorganic and organic molecular building blocks for the construction of supramolecular compounds. The bhmbpy is basically inclined to give single metal-organic subunits based on the chelated coordination mode, resulting in the cis configuration [14b, 15]. The bhmbpy has the flexibility and conformational freedom of the CH2OH groups. As a result, the C-O bonds could rotate freely to satisfy the requirement of hydrogen-bond building. By comparison, Keggin-polyoxometalates have a relatively large volume, resulting in a relatively weak coordination ability. Keggin-polyoxometalates could not only play a charge-compensating role, but also influence the overall structures of supramolecular compounds through formation of hydrogen bonds or coordination bonds [2, 4–9, 13, 14].