The Role of Shape and Size of Guest Molecules in the Formation of Clathrates and Intercalates of Syndiotactic Polystyrene

β-Cyclodextrin (β-CD) is an oligosaccharide composed of seven units of D-(+)-glucopyranose joined by α-1,4 bonds, which is obtained from starch. Its singular trunk conical shape organization, with a well-defined cavity, provides an adequate environment for several types of molecules to be included. Complexation changes the properties of the guest molecules and can increase their stability and bioavailability, protecting against degradation, and reducing their volatility. Thanks to its versatility, biocompatibility, and biodegradability, β-CD is widespread in many research and industrial applications. In this review, we summarize the role of β-CD and its derivatives in the textile industry. First, we present some general physicochemical characteristics, followed by its application in the areas of dyeing, finishing, and wastewater treatment. The review covers the role of β-CD as an auxiliary agent in dyeing, and as a matrix for dye adsorption until chemical modifications are applied as a finishing agent. Finally, new perspectives about its use in textiles, such as in smart materials for microbial control, are presented.

Download Full-text

The role of ice particle shape and size distributions in polarimetric radar measurands at 95 GHz

IEEE 1999 International Geoscience and Remote Sensing Symposium. IGARSS'99 (Cat. No.99CH36293) ◽

10.1109/igarss.1999.773430 ◽

2003 ◽

Author(s):

H. Lemke ◽

M. Quante ◽

O. Danne ◽

E. Raschke

Keyword(s):

Particle Shape ◽

Size Distributions ◽

Polarimetric Radar ◽

Shape And Size

Download Full-text

The Role of Guest Molecules in the Self-Assembly of Metal-Ligand Clusters

ChemInform ◽

10.1002/chin.200301261 ◽

2003 ◽

Vol 34 (1) ◽

pp. no-no

Author(s):

Darren W. Johnson ◽

Kenneth N. Raymond

Keyword(s):

Self Assembly ◽

The Self ◽

Guest Molecules ◽

Metal Ligand

Download Full-text

Intrinsic Flexibility of the EMT Zeolite Framework Under Pressure

10.26434/chemrxiv.7588733 ◽

2019 ◽

Author(s):

Antony Nearchou ◽

Mero-Lee U. Cornelius ◽

Jonathan M. Skelton ◽

Zoe Jones ◽

Andrew Cairns ◽

...

Keyword(s):

Free Energy ◽

Computational Modelling ◽

Lattice Energy ◽

Vibrational Entropy ◽

Organic Additives ◽

X Ray Diffraction ◽

Zeolite Framework ◽

Guest Molecules ◽

Fau Zeolite

<p>The roles of organic additives in the assembly and crystallisation of zeolites is still not fully understood. This is important when attempting to prepare novel frameworks to produce new zeolites. We consider 18-crown-6 ether as an additive, which has previously been shown to differentiate between the EMT and FAU zeolite frameworks. However, it is unclear whether this distinction is dictated by influences on the metastable free-energy landscape or geometric templating. Using high pressure synchrotron X-ray diffraction, we have observed that the presence of 18C6 does not impact the EMT framework flexibility – agreeing with our previous geometric simulations and suggesting that 18C6 does not behave as a true geometric template. This was further studied with computational modelling, using first-principles comparative periodic DFT and lattice-dynamics calculations. It is shown that the lattice energy of FAU is more stable than EMT, however this is strongly impacted by the presence of solvent/guest molecules in the framework. Furthermore, the EMT topology possesses a greater vibrational entropy, being stabilised by free energy at finite temperature. Overall, these findings demonstrate that the role of the 18C6 additive is to influence the free-energy of crystallisation to assemble the EMT framework as opposed to FAU. </p>

Download Full-text

Harnessing Electrostatic Interactions for Enhanced Conductivity in Metal-Organic Frameworks

Research ◽

10.34133/2021/9874273 ◽

2021 ◽

Vol 2021 ◽

pp. 1-11

Author(s):

An-An Zhang ◽

Xiyue Cheng ◽

Xu He ◽

Wei Liu ◽

Shuiquan Deng ◽

...

Keyword(s):

Electrostatic Interaction ◽

Electrostatic Interactions ◽

Metal Organic Frameworks ◽

Electron Conduction ◽

Guest Molecules ◽

Type Semiconductor ◽

Metal Organic ◽

Application Potential ◽

Enhanced Conductivity

The poor electrical conductivity of metal-organic frameworks (MOFs) has been a stumbling block for its applications in many important fields. Therefore, exploring a simple and effective strategy to regulate the conductivity of MOFs is highly desired. Herein, anionic guest molecules are incorporated inside the pores of a cationic MOF (PFC-8), which increases its conductivity by five orders of magnitude while maintaining the original porosity. In contrast, the same operation in an isoreticular neutral framework (PFC-9) does not bring such a significant change. Theoretical studies reveal that the guest molecules, stabilized inside pores through electrostatic interaction, play the role of electron donors as do in semiconductors, bringing in an analogous n-type semiconductor mechanism for electron conduction. Therefore, we demonstrate that harnessing electrostatic interaction provides a new way to regulate the conductivity of MOFs without necessarily altering the original porous structure. This strategy would greatly broaden MOFs’ application potential in electronic and optoelectronic technologies.

Download Full-text