The Influence of Gravity on Single Crystallization in Large Volume Drops

The chemical, physical, and biological properties of more than two millions of proteins which follow to be synthesized by Pharmaceutical Industry, can be anticipated (by using their XRD diffrac-tograms) if they will be grown from aqueous drops as high quality, large volume single-crystals. This is not a simple task and usually the growing process is seen as art rather than a science. The growing is expensive, time consuming, and finally an amorphous aggregate may result instead one single-crystal. In this article, we show for the first time how one single crystal can be grown in large volume hanging drops through their fast evaporation. The single nucleation is determined by choosing the proper sense of gravitational force relative to the drop triple line contact. In a special configuration, single-crystals of glycine and threonine were rapidly grown.

Molecular mechanisms for interaction of glycine betaine with supra-molecular phycobiliprotein complexes

Glycine betaine(GB) is a biologically important small molecule protecting cells,proteins and enzymes in vivo and in vitro under environmental stresses.Recently,it was found that GB could also relax the structure and inactivate the function of phycobiliproteins and phycobilisome(PBS),a kind of supramolecular complexes,in cyanobacterial cells.The molecular mechanisms for the opposite phenomena are quite ambiguous.Taking PBS and a trimeric or monomeric C-phycocyanin(C-PC) as models,the molecular mechanism for the interaction of GB with supra-molecular complexes or nuclear proteins was investigated.The energetic decoupling of PBS components induced by GB suggests that the PBS core-membrane linking polypeptide was the most sensitive site while the rod-core linker was the next.Biochemistry analysis proves that PBS structure was loosened but not dissociated into the components.On the basis of the results and structure knowledge,it was proposed that GB screened the electrostatic attraction of the opposite charges on a linker and a protein leading to a much looser structure.It was observed that GB induced a spectral blue shift for trimeric C-PC but a red shift for a monomeric C-PC(a nuclear protein),which were ascribed to GB's screening of the electrostatic attraction of a linker to a protein and strengthening of the hydrophobic interaction between C-PC monomers.The trimers and monomers' forming of the same products under high concentration of GB was ascribed to a compromise of the opposite interaction forces.

Synthesis and cytotoxic evaluation of substituted 3-(3'-indolyl-/3'-pyridyl)-isoxazolidines and bis-indoles

Regio-and stereoselective 1,3-dipolar cycloadditions of C-(3-indolyl)-N-phenylnitrone(10)were carried out with different mono-substituted,disubstituted and cyclic dipolarophiles under mono-mode microwave irradiation to obtain substituted 3-(indol-30-yl)-N-phenyl-isoxazolidines(16–22).Reactions of nitrone(10)with allenic esters under similar conditions afforded,via a domino process,bis-indole derivatives(23a–c)along with compounds 24 and 25.Similarly,reactions of C-(3-pyridyl)-N-phenylnitrone(26)with mono-substituted,disubstituted and cyclic dipolarophiles were carried out in refluxing dry toluene to obtain substituted 3-(30-pyridyl)-Nphenylisoxazolidines(27–34).Some of the compounds(16f,18b,23a,23c,27c and 29f)display significant cytotoxicity against a number of human cancer cell lines.

Synthesis and Flash Photolysis Studies of 1,3,3,2'-tetramethyl-9'-methoxy Indolinospironaphthoxazine

A new spirooxazine,1,3,3,2′-tetramethy1-9′-methoxyspiro [-2H-indole-2,3′-[-3H] naphth[2,1-b] [-1,4′] oxazine] (Ⅰ) was synthesized.Its photochromic process was studied using nanosecond time-resolved absorption spectroscopy techniques.After irradiation of I with 248 nm laser pulse,a short-lived col-ored species with two absorption bands was observed.In cyclohexane the two bands appear at 470 nm and640 nm,while in acetonitrile at 460 nm and 670 nm.The kinetics for the decay of the colored species is first-order,and its lifetimes are 0.5 μs in cyclohexane and 1.3 μs in acetonitrile.From these results,this short-lived species is assumed to be an intramolecular charge-transfer (CT) intermediate instead of photomero-cyanines (PMC).No absorption band of PMC has been found.The phenomenoncan be interpreted by theproposed potential energy curve.

Photoinduced energy transfer and charge transfer on squarylium cyanine dyes

A series of squarylium cyanine dyes (Sqs) were synthesised to explore their applications in functional devices. Preliminary investigation on the mechanism involved in these devices was carried out. Spectroscopic behavior of Sqs with porphyrin (P), 8-hydroxyquinolium aluminum (Alq) and ruthenium bipyridyl complex (Ru(bipy)) in solution, in film and on nanocrystalline TiO2 was investigated, respectively. A mechanism including photoinduced energy transfer and charge transfer processes was suggested in the corresponding practical devices. By means of doping, a red organic electroluminescent device (ELD) using Sq-doped Alq as the emission layer (EML) has been developed, and the total light to electricity efficiency of nanocrystalline TiO2 electrode based on using Sq-doped Ru(bipy) M photosensitizer has been improved greatly in the whole visible region, particularly in the red area above 600 nm.