Qiang Xiao

Photochromic Diarylethene for Two-Photon 3D Optical Storage

The photochromic diarylethene, 1, 2-bis(2-methyl-5-(3-trifluorophenyl)-3-thienyl)perfluorocyclopentene (BMTTP), was synthesized. This compound undergoes a photochromic reaction either in solution, PMMA amorphous film or in the single crystalline phase. Using this compound as recording medium, two-photon optical bit pattern storage was performed successfully by a femtosecond laser and a reflection confocal scanning-fluorescence microscope.

A P(V)-N activation strategy for the synthesis of nucleoside polyphosphates.

A general and high-yielding synthesis of nucleoside 5-triphosphates (NTPs) and nucleoside 5-diphosphates (NDPs) from protected nucleoside 5-phosphoropiperidates promoted by 4,5-dicyanoimidazole (DCI) has been developed. (31)P NMR tracing experiments showed that the sequential deprotection and coupling reactions were exceptionally clean. The phosphoropiperidate exhibited superior reactivity to the conventional phosphoromorpholidate toward DCI-promoted NTP/NDP synthesis. The experimental results suggested that the mechanism of DCI activation could be distinctive for NTP and NDP synthesis, depending on the different nucleophilicity of pyrophosphate and phosphate.

A highly efficient and selective synthesis of 1,2,3-triazole linked saccharide nucleosides via "click chemistry".

A series of 1,2,3-triazole linked saccharide nucleosides were synthesized in high yield and selectivity via “click chemistry” of the 3′-azido-2′-deoxythymidine and the propargyl carbohydrates.

Synthesis of bifunctional Gd2O3:Eu3+ nanocrystals and their applications in biomedical imaging

Abstract Ultrafine Gd 2 O 3 :Eu 3+ nanocrystals were successfully prepared by a simple reverse microemulsion method and subsequent calcination. Their structural, optical and magnetic properties were investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR), photoluminescence (PL), and magnetic property measurement system (MPMS). The amorphous Gd 2 (CO 3 ) 3 :Eu 3+ colloidal spheres were proved as an intermediate product, and gradually transformed into crystallized Gd 2 O 3 :Eu 3+ with average diameter less than 100 nm. The paramagnetic property of the synthesized Gd 2 O 3 :Eu 3+ nanocrystals were confirmed with its linear hysteresis plot ( M - H ). And Gd 2 O 3 :Eu 3+ nanocrystals showed high contrast T 1 -enhancing modality due to the presence of the Gd 3+ ions onto the particle surface. In addition, the application of the Gd 2 O 3 :Eu 3+ nanocrystals as biotag for cell labeling was reported, red fluorescence from Eu 3+ ions observed by fluorescence microscopy showed that the nanocrystals could permeate the cell membrane. Cytotoxicity studies of the Gd 2 O 3 :Eu 3+ nanocrystals showed no adverse effect on cell viability, evidencing their high biological compatibility. Therefore, the nanoprobe formed from Gd 2 O 3 :Eu 3+ nanocrystals provided the dual modality of optical and magnetic resonance imaging.

Concise total synthesis of two marine natural nucleosides: trachycladines A and B

Summary We report the first total synthesis of trachycladines A (10 steps, 34.2% overall yield) and B (11 steps, 35.0% overall yield) by using 5-deoxy-1,2,3-tri-O-acetyl-β-D-ribofuranose as the starting material. The critical step was the SnCl4 assisted regio- and steroselective deprotection of perbenzylated 1-O-methyl-5-deoxyribofuranose. The enzyme adenylate deaminase (EC 3.5.4.6) was successfully applied to the chemoenzymatic synthesis of trachycladines B.

Synthesis and enzymatic evaluation of phosphoramidon and its β anomer: Anomerization of α-l-rhamnose triacetate upon phosphitylation

A novel and efficient strategy for the synthesis of phosphoramidon and its β anomer has been developed by manipulating the anomerization of α-l-rhamnose triacetate upon phosphitylation. The experimental results suggest that proton transfer, bond rotation, and N atom are the key factors for the anomerization. The determined Ki and Kd values establish that phosphoramidon prepared by this method possesses excellent biological activity, and indicate that the contacts of rhamnose moiety with the enzyme have limited contribution to the binding.

Synthesis of 5-(Carbohydrate-ethynyl)-2 '-deoxyuridine Derivatives

Sonogashira reaction has been successfully applied to the synthesis of a series of 5-(carbohydrate-ethynyl)-2-deoxyuridines for the first time. The synthetic route is general, high-yielding and compatible with the readily removable protecting group.

Synthesis of a novel dithienylethene and application to holographic optical storage

A novel photochromic dithienylethene, [1-(2-methyl-5-formyl-3-thienyl)-2-(2-methyl-5-naphthyl-3-thienyl)]perfluoro- cyclopentene (1a), was synthesized and its photochemical properties, such as photochromism in solution as well as in poly-methylmethacrylate (PMMA) amorphous film, fluorescence were investigated in detail. Dithienylethene 1a has shown good photochromic behavior both in solution and in PMMA film. Upon irradiation with 254 nm UV light, its color changed from colorless to blue, in which absorption maxima were observed at 584 nm in hexane and 596 nm in PMMA film. 1a also showed relatively strong fluorescence in different solvents when excited at 292 nm. In addition, photon-mode holographic optical storage using dithienylethene 1b as recording medium was performed successfully.

Mesoporous silica coated Gd2(CO3)3:Eu hollow nanospheres for simultaneous cell imaging and drug delivery

In the present work, mesoporous silica coated Gd2(CO3)3:Eu hollow nanospheres (Gd2(CO3)3:Eu@mSiO2 HNSs) were successfully synthesized via a facial route and characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscope (SEM) infrared spectrometer (IR), energy dispersive X-ray spectrum (EDS) and Brunauer–Emmet–Teller (BET) surface area analysis. The results indicate that the prepared monodispersed nanoparticles are hollow spheres with a 400 nm sphere core and 30 nm thick shell and have a narrow size distribution. In vitro cell imaging of the hollow nanosphere shows Gd2(CO3)3:Eu@mSiO2 HNSs were able to enter NCI-H460 lung cancer cells rapidly. The possibility of using the synthesized hollow nanospheres for magnetic resonance imaging was also demonstrated, and the hollow nanosphere displays a clear T1-weighted effect and could potentially serve as a bimodal T1-positive contrast agent. The drug loading and controlled release performance of Gd2(CO3)3:Eu@mSiO2 HNSs was evaluated with doxorubicin hydrochloride (DOX) as a model drug at different pH values (pH = 7.4, 5.8). The Gd2(CO3)3:Eu@mSiO2 HNSs showed sustainable pH dependent drug release property. Furthermore, the in vitro cytotoxic effect against NCI-H460 lung cancer cells of the DOX-loaded carriers was investigated in detail. In all, the Gd2(CO3)3:Eu@mSiO2 HNSs as a new type of theragnostic (imaging and treatment) agent can provide new opportunities in cancer treatment.

Synthesis and electrochemical properties of a novel asymmetric dithienylethene compound

A novel asymmetric photochromic compound [1-(2-methyl-5-formyl-3-thienyl)-2-(2-methyl-5-phenyl-3-thienyl)] perfluorocyclopentene (1a) was synthesized and its photochromic and electrochemical properties were investigated. Dithienylethene 1a changed the color from colorless to blue upon irradiation with 254 nm UV light in hexane solution and in PMMA, in which absorption maxima were observed at 590 nm and 604 nm, respectively. Electrochemical reduction of 1a results in the blue ring-closed (1b) by cyclic voltammetry test.