Effects on Solid-State Properties

SCHEME 29. Comparison of optical purity during titration with aq NaOH. 

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Jens and I started an attempt at a systematic, rigorous inclusion of electron correlation effects on solid-state properties. We hailed both from a quantum chemistry tradition of formal clarity, analytical and numerical care, and attention for efficient programming techniques. On the other hand, the solid-state theory tradition followed, and continues to travel a very different route. This path is... 

Catalytic Enantioselective Alkylation / 258 Diastereomeric Interaction of Enantiomers / 278 Effects on Solid-State Properties / 279 Effects in Solution / 281 References / 293... 

The AMI calculations performed for 2,2 -bis-2//-pyrans 294 were used as approximate MO models of thermo- and piezochromic benzo effects to establish X-substituent effects on solid-state properties. The radicals formed by the 2,2 -homolysis of 294-like molecules have been proposed to be colored species. Molecular orbital calculations have suggested very slight electronic effects but an important steric substituent effect on the C(2)—C(2 ) bond length [92JCS(P2)59]. 

V. EFFECT OF CHAIN BRANCHING ON SOLID STATE PROPERTIES... 

Pal SK, Itkis ME, Tham PS, Reed RW, Oakley RT, Donnadieu B, Haddon RC (2007) Phenalenyl-based neutral radical molecular conductors substituent effects on solid-state structures and properties. J Am Chem Soc 129 7163-7174... 

FIGURE 3.22 DSC traces of griseofulvin (a) quenched, (b) quenched after 9 months storage under ambient conditions, (c) quenched followed by size reduction, (d) quenched (slower solidification), and (e) raw material. (Reproduced from Mosharraf, M., The Effects of Solid State Properties on Solubility and In Vitro Dissolution Behaviour of Suspended Sparingly Soluble Drugs, Ph.D. thesis, University of Uppsala, 1999. With permission.)... 

Mosharraf, M., The Effects of Solid State Properties on Solubility and In Vitro Dissolution Behaviour of Suspended Sparingly Soluble Drugs, Ph.D. thesis, University of Uppsala, 1999. 

The effect of MW and MWD on the solid state properties have been extensively studied [11,12,82]. These studies have been made both on fractionated and whole polymer samples. Attempts have also been made to correlate the solution viscosity, melt viscosity, MFI and other related parameters, which represent the MW and MWD of the polymers, with the solid state properties. Table 6 summarizes the results of various studies on effect of MW and MWD on the properties of PEs. 

The phenomenon of pseudopolymorphism is also observed, i.e., compounds can crystallize with one or more molecules of solvent in the crystal lattice. Conversion from solvated to nonsolvated, or hydrate to anhydrous, and vice versa, can lead to changes in solid-state properties. For example, a moisture-mediated phase transformation of carbamazepine to the dihydrate has been reported to be responsible for whisker growth on the surface of tablets. The effect can be retarded by the inclusion of Polyoxamer 184 in the tablet formulation [61]. 

The pharmaceutical industry has taken great interest of late in the study of polymorphism and solvatomorphism in its materials, since a strong interest in the phenomena has developed now that regulatory authorities understand that the nature of the structure adopted by a given compound upon crystallization can exert a profound effect on its solid-state properties. For a given material, the heat capacity, conductivity, volume, density, viscosity, surface tension, diffusivity, crystal... 

QSPRs in which solubilities and vapor pressures are correlated against molecular structure are done exclusively using the liquid state property. This avoids the complication introduced by the effect of fugacity ratio or melting point on the solid state property. 

Yu, L., and Perret, J. (2003a). Effects of solid-state enzyme treatments on the water-absorbing and gelling properties of psyllium. LWT-Food Sci. Technol. 36, 203-208. 

Chowhan, Z. T.. and Chi, L. H. Drug-excipient interactions resulting from powder mixing. Part 3. Solid-state properties and their effect on drug dissolution. J. Pharm. Sci. 75 534-541, 1986. 

The Hamiltonian Eq. (7) provides the basis for the quantum dynamical treatment to be detailed in the following sections, typically involving a parametrization for 20-30 phonon modes. Eq. (7) is formally equivalent to a class of linear vibronic coupling (LVC) Hamiltonians which have been used for the description of excited-state dynamics in molecular systems [66] as well as the Jahn-Teller effect in solid-state physics. In the following, we will elaborate on the general properties of the Hamiltonian Eq. (7) and on quantum dynamical calculations based on this Hamiltonian. 

The effect of the length of the side chain and the presence of the carboxylic group have been taken into account to explain the particular conformational behavior of some of these poly(itaconate)s [191,192], The effect of the length of the side group and the presence of the carboxylic group are the responsible of the particular conformational behavior of some poly(monoitaconate)s [191, 192], On the other hand poly(di-n-alkyl itaconate)s obtained from diester of itaconic acid and lower unbranched alcohols, show important changes in both solution and the solid state properties [182-185],... 

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