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Textile and Other Odours: A Focus on Third-hand Smoke and Laundry Odour
Published in G. Thilagavathi, R. Rathinamoorthy, Odour in Textiles, 2022
R. Rathinamoorthy, G. Thilagavathi
The fundamental reason for the reduction of THS release is the entrapment of odour molecules in the MCT-β-CD structure. MCT-β-CD engages the hydroxyl reactive sites in the cellulose chain of the cotton structure. The reaction permanently bonds the finish to cotton fabric through a covalent bonding as MCT acts as a reactive anchor. The complete fixing of MCT-β-CD helps the complexing reaction of CD with the THS from the sources, like nitrosamine and benzene, on the surface of the cellulose. This complex formation is expected to happen by noncovalent physical interactions, such as van der Waals forces, H-bonds, and hydrophobic attractions. Due to the hydrophobic nature of CD, it provides a suitable environment for the host material complexing. The positively charged b-cyclodextrin cavity forms a hydrogen bond with the nitrosamine molecules, by replacing oxygen in the -N-N=O, through a HO- bond with the rim of b-cyclodextrin and complexes the nitrosamine within the b-cyclodextrin. Similarly, the alkyl group was trapped into the wider rim of the b-cyclodextrin cavity. As the volatile components are not only trapped into the cavity of the b-cyclodextrin but also interact through hydrogen bond (Wang et al. 2004), the complexing phenomenon is noted as a strong option for the reduction of THS release from the textile.
ab initio theoretical study
Published in Alberto Figoli, Jan Hoinkis, Sacide Alsoy Altinkaya, Jochen Bundschuh, Application of Nanotechnology in Membranes for Water Treatment, 2017
Giorgio De Luca, Federica Bisignano
Moreover, when QC procedures are used, attention has to be paid to the structural models since they dramatically affect the computational time required for the calculations. The structural models, in turn, are also dependent on the properties to be assessed (De Luca, 2013). For example, if non-covalent binding energies have to be calculated, the associated structural model, such as a carbon nanotube with guest molecules inside, must contain a sufficient number of atoms to obtain reliable energies. In this chapter, the QC calculations were carried out on systems having large numbers of atoms (up to 700), and although high computational time was required, accurate energies associated with the non-covalent interactions and molecular structures involved in the target systems were achieved. The non-covalent interactions play an important role and control many nanostructure system features. However, for flexible molecules, molecular mechanics calculations were also carried out in order to have an accurate description of the conformational space of these systems. A brief introduction to DFT, used in the QC calculations, now follows.
Current and Future Applications of Diamondoids and Their Derivatives
Published in Sven Stauss, Kazuo Terashima, Diamondoids, 2017
Host–guest chemistry involves binding of a guest molecule by a host molecule, the bond between the molecules being noncovalent. Noncovalent bonds can involve hydrogen bonds, ionic bonds, van der Waals forces, or hydrophobic interactions. Examples of diamondoids acting as hosts in host–guest chemistry are given in (Voskuhl et al., 2012). In this specific work, diamondoids are included inside sugar rings. There are other possible guest molecules, for example, cyclodextrins, calixarenes, pillararenes, cucurbiturils, porphyrins, metallacrowns, crown ethers, zeolites, cyclotriveratrylenes, cryptophanes, carcerands, and foldamers. One example of a host molecule that is obtained by substitution by 1-adamantyl is calix[4]arene.
Pursuing the basis set limit of CCSD(T) non-covalent interaction energies for medium-sized complexes: case study on the S66 compilation
Published in Molecular Physics, 2023
Péter R. Nagy, László Gyevi-Nagy, Balázs D. Lőrincz, Mihály Kállay
Non-covalent intermolecular interactions are ubiquitous and play a key role in a large number of (bio)chemical systems. The precise and efficient modelling of intermolecular interactions is still one of the great challenges of computational modelling since accurate description is required for a large number of individually small but cumulatively important interaction components. Since electron correlation effects have to be taken into account due to the required sub-kcal/mol accuracy, a number of wave function based methods have been made available for intermolecular interaction computations [1–4]. Among others, the application of the symmetry-adapted perturbation theory (SAPT) [5–7], diffusion Monte Carlo (DMC) [8–11], random phase approximation (RPA) [12, 13], and coupled-cluster (CC) methods [14], in particular the gold standard CC model with single and double excitations (CCSD), augmented with perturbative triples correction [CCSD(T)] [15] have been particularly successful in this context.
Non-covalent interactions in clathrate complexes
Published in Journal of Coordination Chemistry, 2021
Janusz Lipkowski, Hans-Jörg Schneider
We discuss here essentially van der Waals contributions, which have been demonstrated recently to play an underestimated role in many supramolecular solution complexes [26]. Dispersive interactions present one of the most ubiquitous non-covalent forces; a single interaction is among the weakest, but with larger molecular surfaces in van der Waals contacts their sum can overweigh all other interactions. In solid state these van der Waals interactions often prevail, as exemplified by the sublimation energy of 38 kJ/mol for cyclohexane, or 42 kJ/mol for benzene [15]. In solution, dispersive interactions between host and guest are often diminished by interaction with excess bulk solvent, in particular if the solvent is, as in most organic media, characterized by high polarizability. Hunter [27] and others [28] have brought forward many arguments against a significant role of dispersive interactions in condensed media, but these arguments could be dismissed [26] by measurements in particular in water, a medium of exceptionally low polarizability. As expected C-H bonds in hydrocarbons exert in solution very small, if any, interaction energies, while the presence of aromatic groups or heteroatoms lead to complexation free energies which essentially increase with their polarizability.
Tuning of non-covalent interactions involving a halogen atom that plays the role of Lewis acid and base simultaneously
Published in Molecular Physics, 2018
The formation of molecular complexes is a phenomenon which has attracted much attention over the last decades [1–5]. Molecular complexes are defined as systems whose individual fragments (most often simply molecules) are held together by non-covalent (in other words intermolecular) interactions. Non-covalent interactions are a broad category of interactions and in the most general sense, they actually span everything except for covalent interactions, i.e. interactions associated with the overlap of electronic density in the bonding region between interacting fragments with unfilled electronic shells, which lead to the formation of a chemical bond and a new molecule [6]. Among non-covalent interactions, hydrogen bonding (HB) and halogen bonding (XB) have received probably most of the attention due to the fact that these interactions play an important role in many areas of chemistry and physics [7,8], e.g. in biochemical processes [9–12], crystal engineering [12–16] and material science [12,17,18]. They have also become one of the main topics in computational chemistry and physics in recent years [12,19,20].