Non-specific bonding

Reaction kinetics and bonding energies are additional tools useful for examination of ligand bonding to oxide surfaces. Non-specific bonds should result in rapid desorption reaction kinetics, while monodentate and bidentate and binuclear bonds should be correspondingly more difficult to break. 

Fig. 23.3. Inelastic neutron scattering spectra of y-MnOj powder. The spectrum of the sample is recorded at 4 K and the spectrum of the same sample heated previously at 450 "C has been subtracted. Bonds are assigned to localized protons (OH .HjO) whereas the diffuse and broad continuum above 100cm seems related to a proton gap (proton lattice gap) (with courtesy ). The INS spectrum of Ho.ssMnOj prepared by chemical reduction of y-MnOj shows three peaks near 1120, 2200 and 3100 cm which are assigned to the 0 - 1, 0 - 2 and 0 — 3 transitions of an isotropic oscillator, respectively. This triplet may correspond to a non-specific bonded proton at the centre of the octahedral cavity .

Independent molecules and atoms interact through non-bonded forces, which also play an important role in determining the structure of individual molecular species. The non-bonded interactions do not depend upon a specific bonding relationship between atoms, they are through-space interactions and are usually modelled as a function of some inverse power of the distance. The non-bonded terms in a force field are usually considered in two groups, one comprising electrostatic interactions and the other van der Waals interactions. 

Attempts have also been made to separate non-specific effects of the local electrical field from hydrogen-bonding effects for a small group of ionic liquids through the use of the k scale of dipolarity/polarizability, the a scale of hydrogen bond donor acidity, and the (i scale of hydrogen bond basicity (see Table 3.5-1) [13, 16]. 

Even simple dienes and polyenes are difficult to classify in comparison with alkenes. Whereas bromination, oxidation and reaction with tetranitromethane (TNM) can identify the number of double bonds and their location in the molecular structure, conjugated double bonds produce very complex mixtures. Furthermore, many of the tests based on 7r-complexation can also apply for aromatic moieties. An example is the TNM 7r-complex which is yellow with benzene and orange with naphthalene and the tests are therefore non-specific. 

Table 3.41. NBO/NRT descriptors for B4H10 (see Fig. 3.103(a)), showing (a) alternative styx codes (with specific bond types) and associated non-Lewis density error (b) NHO hu and percentage polarization for NBOs of the...

These are defined as anionic dyes with substantivity for cellulosic fibres applied from an aqueous dyebath containing an electrolyte. The forces that operate between a direct dye and cellulose include hydrogen bonding, dipolar forces and non-specific hydrophobic interaction, depending on the chemical structure and polarity of the dye. Apparently multiple attachments are important, since linearity and coplanarity of molecular structure seem to be desirable features (section 3.2.1). The sorption process is reversible and numerous attempts have been made to minimise desorption by suitable aftertreatments (section 10.9.5). The two most significant non-textile outlets for direct dyes are the batchwise dyeing of leather and the continuous coloration of paper. 

This scheme disregards mass transfer limitations and represents only a simplified model. Formation of A S may involve specific interactions, such as hydrogen bonds, coordination, or ir-complex formation, or non-specific interactions, such as van der Waals or hydrophobic bonds. Non-specific interactions are insignificant for small polar molecules, but may contribute significantly to the surface complex formation if the hydrophobic moiety is large ( 5, 6) ... 

Theory Alkaline phosphatase is responsible for the cleavage of O-P bonds. It is found to be relatively non-specific and this characteristic permits the AP level to be assayed based on the fact that/i-nitrophcnylphosphate ion gets converted top-nitrophenolate anion at pH 10.5 as expressed in the following reaction. 

CNTs can be functionalized with protein via non-covalent bond (Li et al., 2005 Kim et al., 2003 Mitchell et al., 2002). For example, (beta-lactamase I, that can be immobilized inside or outside CNTs, doesn t change enzyme s activity (Vinuesa and Goodnow, 2002). Taq enzyme can attach to the outside of CNT, and doesn t change its activity (Cui et al., 2004). Peptide with Histidine and Tryptophan can have selective affinity for CNT(Guo et al., 1998). Monoclonal antibody can attach to SWNTs. Protein-modified CNTs can be used to improve its biocompatibility and biomolecular recognition capabilities (Um et al., 2006). For example, CNTs functionalized with PEG and Triton X-100 can prevent nonspecific binding of protein and CNTs. Biotin moiety is attached to the PEG chains Streptavidin can bind specifically with biotin-CNT (Shim et al., 2002). 

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