Disordered interfaces of alkaline aluminate salt hydrates provide glimpses of Al coordination changes.

Hypothesis: The precipitation and dissolution of aluminum-bearing mineral phases in aqueous systems often proceed via changes in both aluminum coordination number and connectivity, complicating molecular-scale interpretation of the transformation mechanism. Here, the thermally induced transformation of crystalline sodium aluminum salt hydrate, a phase comprised of monomeric octahedrally coordinated aluminate which is of relevance to industrial aluminum processing, has been studied. Because intermediate aluminum coordination states during melting have not previously been detected, it is hypothesized that the transition to lower coordinated aluminum ions occurs within ahighly disordered quasi-two-dimensional phase at the solid-solution interface.

Theory-Guided Inelastic Neutron Scattering of Crystalline Alkaline Aluminate Salts Bearing Principal Motifs of Solution-State Species.

Aluminate salts precipitated from caustic alkaline solutions exhibit a correlation between the anionic speciation and the identity of the alkali cation in the precipitate, with the aluminate ions occurring either in monomeric (Al(OH)) or dimeric (AlO(OH)) forms. The origin of this correlation is poorly understood as are the roles that oligomeric aluminate species play in determining the solution structure, prenucleation clusters, and precipitation pathways. Characterization of aluminate solution speciation with vibrational spectroscopy results in spectra that are difficult to interpret because the ions access a diverse and dynamic configurational space.

Solid-State Recrystallization Pathways of Sodium Aluminate Hydroxy Hydrates.

Crystallization of Al-bearing solid phases from highly alkaline NaO:AlO:HO solutions commonly necessitates an Al coordination change from tetrahedral to octahedral, but intermediate coordination states are often difficult to isolate. Here, a similar Al coordination change process is examined during the solid-state recrystallization of monosodium aluminate hydrate (MSA) to nonasodium bis(hexahydroxyaluminate) trihydroxide hexahydrate (NSA) at ambient temperature. While the MSA structure contains solely oxolated tetrahedral Al, the NSA structure is a molecular aluminate salt solely based upon monomeric octahedral Al.

Fluorescent H-aggregates of an asymmetrically substituted mono-amino Zn(ii) phthalocyanine.

The photophysical properties of a newly synthesized unsymmetrically substituted zinc phthalocyanine derivative (1) bearing in its peripheral positions six n-hexylsulfanyl substituents and one amino-terminated n-hexylsulfanyl substituent were investigated. This mono-amino phthalocyanine exhibited a high tendency to form H-type aggregates in all of the investigated solvents: dichloromethane (DCM), tetrahydrofuran (THF) and dimethyl sulfoxide (DMSO). Several species of H-aggregates were present together in relatively broad concentration ranges in THF and DCM, whereas in DMSO they were observed separately depending on the concentration used.

A theoretical study of the structure-radical scavenging activity of trans-resveratrol analogues and cis-resveratrol in gas phase and water environment.

Quantum calculations based on the density functional theory (DFT) have been employed to study the relation between the structure and antioxidant activity of trans-resveratrol (TR), cis-resveratrol (CR), trans-4.4'-dihydroxystilbene (trans-4,4'-DHS), trans-3,4-dihydroxystilbene (trans-3,4-DHS), trans-3,4,4'-trihydroxystilbene (trans-3,4,4'-THS), trans-3,4,5-trihydroxystilbene (trans-3,4,5-THS) and alpha,beta-dihydro-3,4',5-trihydroxystilbene (alpha,beta-dihydro-3,4',5-THS) in the gas phase and water environment. We have shown that the antioxidant activity of trans-stereoisomers of the compounds considered is related to their phenoxy radicals showing a planar and semiquinone conformation that allows delocalization of the unpaired electron through the whole trans-stilbene skeleton.