N-Benzyl HMTA induced self-assembly of organic-inorganic hybrid materials for efficient photocatalytic degradation of tetracycline.

Photocatalytic degradation technology (PDT), as one of the most important advanced oxidation technologies (AOTs) for environment-purifying, have drawn great attentions in recent years. It is highly desirable but remains challenging to design and synthesize catalysts with enhanced performance of photocatalysis. Herein, we develop a cation induced self-assembly strategy for the synthesis of two new organic-inorganic hybrid materials ({[BHMTA][Cu2(SCN)3]}n (1), {[BHMTA][Cu2I3]}n (2) BHMTA = N-benzylhexamethylenetetramine bromide). Owing to their unique structural and the desirable composition, the as-prepared organic-inorganic hybrid materials exhibit high efficiency and excellent cycling stability for degradation of tetracycline (TC) under visible light irradiation. In addition, the effect factors for photocatalysis such as catalyst dosage, temperature, and pH were also investigated. The possible mechanism studied shows that superoxide radicals (O2-) and holes (h+) are the main active substances in the degradation process of TC. This work may shed light on preparing new organic-inorganic hybrid materials with promising photocatalysis performance for water purification.

Synthesis and Characterization of Versatile O-Glycan Precursors for Cellular O-Glycomics.

Protein O-glycosylation is a universal post-translational modification and plays essential roles in many biological processes. Recently we reported a technology termed cellular O-glycome reporter/amplification (CORA) to amplify and profile mucin-type O-glycans of living cells growing in the presence of peracetylated Benzyl-α-GalNAc (Ac3GalNAc-α-Bn). However, the application and development of the CORA method are limited by the properties of the precursor benzyl aglycone, which is relatively inert to further chemical modifications. Here we described a rapid parallel microwave-assisted synthesis of Ac3GalNAc-α-Bn derivatives to identify versatile precursors for cellular O-glycomics. In total, 26 derivatives, including fluorescent and bioorthogonal reactive ones, were successfully synthesized. The precursors were evaluated for their activity as acceptors for T-synthase and for their ability to function as CORA precursors. Several of the precursors possessing useful functional groups were more efficient than Ac3GalNAc-α-Bn as T-synthase acceptors and cellular O-glycome reporters. These precursors will advance the CORA technology for studies of functional O-glycomics.

Why does a para-amino group make the green fluorescent protein chromophore non-fluorescent: coherent intramolecular charge transfer reduces the Z/E-photoisomerization barrier.

A para-N-phenyl-amino group significantly increases the fluorescence quantum yield of N-phenyl-4-aminostilbene by the "amino conjugation effect", but, in contrast, a para-amino group in the para-amino analogue (p-ABDI) of the green fluorescent protein (GFP) chromophore makes p-ABDI non-fluorescent because the coherent photo-induced intramolecular charge transfer reduces the barrier of the Z/E-photoisomerization.

Ultrafast trans-cis photoisomerization of the neutral chromophore in green fluorescent proteins: Surface-hopping dynamics simulation.

Reversible photoswitching fluorescent protein can reversibly switch between on-state (fluorescent) and off-state (dark). Anionic cis and neutral trans chromophores are the on- and off-states in green fluorescent proteins (GFPs), respectively. We investigated the ultrafast trans-cis photoisomerization mechanisms of the neutral GFP chromophore upon excitation to the S1 state by means of surface-hopping dynamics simulations based on the Zhu-Nakamura theory. Two trans isomers, located in the S0 state, were taken into consideration in dynamics simulation. After these two trans isomers are excited to the S1 state, the molecule moves to a excited-state minimum by increasing the imidazolinone-bridge bond length and decreasing the phenol-bridge bond length. The twist of imidazolinone-bridge bond drives the molecule toward a conical intersection, and internal conversion occurs. Then, a cis or trans conformer will be obtained in the S0 state. The torsion around the imidazolinone-bridge bond plays a key role in the ultrafast photoisomerization of a neutral chromophore. The torsional motion around the phenol-bridge bond is restricted in the S1 state, while it may occur in the S0 state. The isomerization reaction of this molecule is predicted to be not sensitive to solvent viscosity, and time-dependent density functional theory (TDDFT) calculations indicate that the fast excited-state decay from the Franck-Condon region of the trans isomer to the excited-state minimum was almost independent of solvent polarity.

Visible light mediated efficient oxidative benzylic sp(3) C-H to ketone derivatives obtained under mild conditions using O2.

A photooxygenation of benzylic sp(3) C-H reaction has been demonstrated using O2 mediated by visible light. This protocol provides a simple and mild route to obtain ketones from benzylic sp(3) C-H bonds. Various benzylic sp(3) C-H bonds can be transformed into the desired ketone derivatives in moderate to good yields. The (18)O2 labelling experiments demonstrated that the oxygen introduced into ketone originated from dioxygen. A plausible mechanism has been proposed accordingly.

Photolysis of dibenzyl ketones sorbed on MFI zeolites in the presence of spectator molecules: cage effects, kinetics, and external surface sites characterization.

Over the past two decades, the photolytic reactions of dibenzyl ketones sorbed on zeolites have been investigated. The reported results are consistent with a supramolecular model that takes into account the physical and chemical nature of the structure of the zeolites and their effect on the reactive radical intermediates produced by photolysis of adsorbed molecules. The model incorporates various phenomena such as surface coverage, external and internal sorption, surface diffusion, radical sieving, and the resulting product distributions. This account reports direct evidence for the validation of the model through FT-IR spectroscopy and through a new method for "titrating" the binding sites via EPR spectroscopy. It is shown that it is possible to adjust and modulate the photolytic product distribution by varying the parameters of the system. The effects of co-adsorbed spectator molecules with different polarities, namely water, pyridine, and benzene, on the photolysis of o-methyldibenzyl ketone and dibenzyl ketone sorbed on MFI zeolites is examined. This study provides insights into a displacement mechanism caused by spectator molecules and further demonstrates how the product distribution of photolysis of sorbed ketones can be controlled. The kinetics of persistent radicals formed by photolysis of ketones sorbed on zeolites is directly monitored over time by EPR, providing a measure of the lifetime of these reactive organic intermediates. Finally, measurement of Langmuir isotherms was employed to provide classical evidence for the model.

Aerobic oxidation of benzyl- and allylic alcohols under visible light irradiation of a fluorescent lamp in the presence of catalytic iodine.

Benzyl alcohols and allylic alcohols were found to be oxidized to the corresponding aldehydes in the presence of a catalytic amount of iodine under irradiation of a fluorescent lamp.

Development of the first potential covalent inhibitors of anandamide cellular uptake.

On the basis of the chemical structures of two previously developed metabolically stable and relatively potent inhibitors of anandamide uptake, OMDM-1,2, two series of potential covalent inhibitors of anandamide cellular reuptake, which might be used for the molecular characterization of the protein(s) involved in the membrane transport of endocannabinoids, have been designed and synthesized. Most of the compounds inhibited uptake to a varied extent and in a generally enantio-sensitive manner when co-incubated with [(14)C]anandamide, but only three of them, the photoactivatable 1a (OMDM-37), 1b (OMDM-39), and 8(Lo395), also produced a significant inhibition of uptake following the preincubation only of the cells, and this effect was significantly enhanced following UV exposure only in the case of 8. None of the new compounds inhibited [(14)C]anandamide hydrolysis with IC(50) < 50 microM, except for 1b.

[Radiolysis of benzyl alcohol in aqueous solution].

Radiolysis of 0.05% aqueous solution of benzyl alcohol with 50Co gamma-rays ranging from 1 X 10(4) to 7 X 10(5) rad was investigated, in order to presume the change of it contained in radiopharmaceuticals. For both O2 free and oxygenated solutions, an approximately linear relationship holds between the retaining benzyl alcohol and dose in the range from 1 X 10(5) to 7 X 10(5) rads. The G(-M) values of benzyl alcohol calculated from the relation were 2.34 in the absence and 1.92 in presence of oxygen. In the presence of oxygen, a main product was benzaldehyde and its G value was 0.87. In the absence of oxygen, the main products of the radiolysis were dibenzyl, benzyl phenylcalbinol and hydrobenzoin, which were regarded as the radicao-reaction products of PhCH2 and PhCHOH, and the yield of benzaldehyde was negligible. Irrespective of the presence of oxygen, o- and p-hhdroxylated products of benzyl alcohol were found only in small quantity.