Intermolecular aggregate

Olivares et al. (2006), studies performed viscometers very dilute gelatin solutions with concentrations between 10-5 and 10-3 g/cm3, where either intermolecular aggregation or intramolecular folding are possible, respectively, and the sol-gel transition is not observed. 

In the case of amphiphilic molecules, characterized by the coexistence of spatially separated apolar (alkyl chains) and polar moieties, both parts cooperate to drive the intermolecular aggregation. This simple but pivotal peculiarity makes amphiphilic molecules soluble in both polar and apolar solvents and able to realize, in suitable conditions, an impressive variety of molecular aggregates characterized by spatially separated apolar and polar domains, local order at short times and fluidity at long times, and differences in size, shape (linear or branched chains, cyclic or globular aggregates, extended fractal-like molecular networks), and lifetime. 

The UV-visible spectra of the H- and nifro-azobenzene dendrimers in chloroform solution showed strong absorption bands within the visible region due to the transitions of azobenzene chromophores (Table 2). Because of the stronger delocalization of n-electrons in nitro-azobenzene, the maximum absorption band is at a longer wavelength compared with that for H-azoben-zene. There was little spectral shift of the absorption maximum for dendrimers with different numbers of azobenzene units, indicating that dendrimers did not form any special intermolecular aggregates. 

Efforts at synthesis and studies of temperature-dependent solution behaviour of these chemically hydrophobized polyacrylamides are now in progress. However, it is reasonable to point out that in this case, contrary to the hydrophilization of the hydrophobic precursor, the problems associated with additional swelling of the globular core (as the modification proceeds) are absent however, the problem of the choice of working concentration for the precursor is still present since above the coil overlapping concentration the intermolecular aggregation processes at elevated temperatures can compete with the intramolecular formation of core-shell structures. 

The Sn6P6 cages 19c and 19d are accessible by two different Bronsted acid-base reaction pathways Reaction of lc and Id, respectively, with two different stannanediyl derivatives furnished in 80-89% yield red-black crystals of the aggregates (Eq. 12) (39). The tin(II) phosphandiides are somewhat related to the previously described oligomeric bis (phosphaneyl) stannanediyls of the type PkSn, which easily form intermolecular aggregates (50, 51) or remain monomeric, if the phosphorus atoms bear very crowded organosilyl substituents (52). 

The possibilities for coordinative bonding and related types of acid base adduct association with closed-shell species are strongly increased, leading to an enhanced tendency toward intermolecular aggregation and condensation. 

Based on the above studies of water-soluble Gd C82 and Gd C60 derivatives, it appears that once Gd3+ is inside the fulleiene cage, the relaxivity properties are largely directed by the nature, number, and disposition of derivative groups. The particulars of intermolecular aggregation (nanoclustering) that result from the chemical composition of derivative groups seems to exert a major influence on... 

High-potential iron proteins, 45 313-314, 344 cluster stability, 45 324-332 function, 45 315-316 residues, 45 322-344 structure and, 45 317-322 redox properties, 45 333-344 solvent accessibility, 45 330, 332-333 source and function, 45 314-316 structure, 45 316-322 hydrogen bonding and, 45 321-322 intermolecular aggregation, 45 322 primary, 45 317-318 secondary and tertiary, 45 318-321... 

Apart from the obvious use of proton NMR spectroscopy as an aid in structure elucidation, the technique has also been used to probe the phenomena of intermolecular aggregation, apical ligand binding, NH tautomerism, rates of protonation, and a host of theoretical aspects. An extensive review of porphyrin and chlorin NMR spectroscopy has appeared... 

The absorption spectra of every molecular wire 470-474 in thin films were nearly identical to those in solution, which implied that the interchain interaction and/or intermolecular aggregation in the ground states might be suppressed in films possibly owing to truxene moieties with hexyl substituents. Their absorption spectra in films show an identical peak at about 309 nm owing to the n n electron absorption band of the truxene units. The absorption Xmax peaked at 400 nm for 470, 410 nm for 471, 415 nm for 472, 418 nm for 473, and 424 nm for 474, respectively. 

Instead of coordinating mono-hapto bases to the protons of (Ph2SiO)8[Al-0(0H)]4, we have explored the field of di-hapto bases like poly methylene diamines as possible donors. As the molecule (Ph2Si0)8[A10(0H)]4 has pairs of hydroxyl groups directed in the same direction a coordination of H2N(CH2) NH2 could either lead to an intramolecular loop or to intermolecular aggregations of molecules. This field of chemistry is actually very much expanding and we give in this review only a small out-look, essentially with the diamines 1,3-diaminopropane, 1,4-diaminobutane and 1,5-diaminopentane. 

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