Quartz Crystal Microbalance Analysis of DNA-Templated Calcium Phosphate Mineralization

A quartz crystal microbalance (QCM) sensor was developed for the quantitation of calcium phosphate mineralization and the assessment of DNA as a template molecule. Inherent advantages of QCM, such as nanogram sensitivity, temporal resolution, surface-based measurements, and flow capabilities, were leveraged in the design of this sensor, and in-line fluidic mixing was used to control precursor reaction. This research shows that DNA, a highly programmable anionic polymer, is able to template and control mineralization of calcium phosphate, with nucleation occurring in less than 15 min and initial rates ranging from 4 to 8 ng/min. FT-IR measurements show mineralized material to be calcium phosphate resembling hydroxyapatite (HAP) when a DNA template is used. DNA is a promising mineralization template, and the QCM proves to be a dynamic technique for a broad range of heterogeneous mineralization experiments in complement to classic, diffusion-limited, end-point analysis techniques.     

Pyridinium salts

New 4- (benzazol-2-yl)pyridinium salts have been synthesized. Their reduction in a neutral medium with sodium tetrahydroborate has given 2-(1,2,5,6-tetrahydropyridin-4-yl)benzazoles. The catalytic hydrogenation of the latter leads to piperidine derivatives which have also been synthesized by an independent route.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 104–107, January, 1974.     

A study of 1,2,3,4-tetrahydro-4-azafluorene-3,9-diones

Intramolecular cyclization of the diamides and N,N-dimethylamides of -[indan-1,3-dion-2-yl]benzylmalonic acids (I) has given 1-aryl-2-carbamoyl-1,2,3,4-tetrahydro-4-azafluorene-3, 9-diones and 1-aryl-4-methyl-2-methylcarbamoyl-1,2,3,4-tetrahydro-4-azafluorene-3,9-diones (II). The structure of compounds II was shown by chemical methods: bromination, xanthylation, and hydrolysis in alkaline and acid media, and also by a study of IR and UV spectra.     

Transformations of substituted tetrahydro-8h-indeno[1,2-d]imidazoles in concentrated sulfuric acid

The five-membered ring of the indene system in 2,8-dioxo-3a-hydroxy-8a-R-1,2,3a,8a-tetrahydro-8H-indeno[1,2-d]imidazoles is hydrolytically cleaved in concentrated sulfuric acid solutions. Depending on the reaction conditions, compounds for which substituted 4-(o-carboxyphenyl)imidazol-2-one (II), 1,8-dioxo-1,2-dihydro-8H-imidazo[4,3-a]isoindole (III), and spiro[imidazolidine-4,3′-phthalide] structures were assumed were isolated.     

Thiourea derivatives ofΒ-dicarbonyl compounds

Under the action of sulfuric acid, N-(2-phenylindan-1,3-dion-2-yl)-thioureas (I) undergo hydrolytic cleavage of the five-membered ring with the subsequent cyclization of the intermediate products formed, thiocarbomido-o-carboxydeoxybenzoins, to give 4-(o-carboxyphenyl)-5-phenylimidazole-2-thiones (III). The structure of compounds III has been confirmed by their IR and UV spectra, and a mechanism for their formation has been proposed. A preparative method for the synthesis of 4-(o-carboxyphenyl)-5-phenylimidazole-2-thiones has been developed.For communication IV, see [16].     

Benzindazoles from indanetriketones

1-Alkyl-5-hydroxybenz[g]indazoles have been synthesized by the reaction of 2-acetonyl- and 2-phenacyl-2-arylindan-1, 3-diones with alkylhydrazines, accompanied by intramolecular cyclization and ring rearrangement.For Part II, see [2].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1258–1260, September, 1970.     

Electrospray mass spectrometry study of tiopronin monolayer-protected gold nanoclusters

Electrospray ionization time-of-flight mass spectrometry (ESI-TOF MS) and gel permeation chromatography (GPC) were used to study the synthesis of a series of tiopronin monolayer-protected gold nanoclusters (MPCs) and to monitor their postsynthesis peptide ligand place-exchange reactions. All mass spectra identified the presence of cyclic gold(I)-thiolates with a strong preference for tetrameric species. During the synthesis of pre-monolayer-protected nanoclusters (pre-MPCs), esterified gold(I)-thiolate tetramers were initially observed in minor abundance (with respect to disulfide bridged tiopronin species) before dramatically increasing in abundance and precipitating from solution. After conversion of pre-MPCs to MPCs, ESI-TOF mass spectra demonstrated an overall predominance of tetrameric species with conversion from ester-terminated end groups to carboxyl-terminated end groups. Further modifications were performed through postsynthesis ligand place-exchange reactions to validate the existence of the tetramers. This work suggests that monolayer protection is accomplished by cyclized gold(I)-thiolate tetramers on the gold core surface, and/or that gold(I)-thiolates are a basic building block within the nanoparticles.     

Benzindazoles based on triketones of the indan series

With phenylhydrazine, 2-acetonyl- and 2-phenacyl-2-phenylindan-1,3-diones form phenylhydrazones at the carbonyl group of the side chain. On prolonged heating, a reaction takes place with the expansion of the five-membered ring into a six-membered ring and the formation of the corresponding 5-hydroxy-1-phenylbenz[g]indazoles. A reaction mechanism is proposed. The structure of the compounds obtained has been confirmed by their IR and UV spectra.