Lin-Jiu Xiao

A turn-on NIR fluorescent probe for the detection of homocysteine over cysteine

A BODIPY-based turn-on NIR fluorescent probe containing a partially exposed aldehyde group at the meso position for the detection of homocysteine over cysteine was developed. Such a probe is potentially useful for the discrimination of Hcy from Cys.

Synthesis of mono-(p-dimethylamino)styryl-containing BOPHY dye for a turn-on pH sensor

Mono-substitutional bis(difluoroboron)1,2-bis((1H-pyrrol-2-yl)methylene)hydrazine (BOPHY) 3a with a (p-dimethylamino)styryl group in the α-position was confirmed to be synthesized by the Knoevenagel-type condensation. Dimethylamino-containing BOPHY dye 3a is almost non-fluorescent by the ICT effect. Upon the protonation of the tertiary amine function of 3a, the strong fluorescence (Φf = 0.98) was released and the fluorescence intensity was dramatically increased by one thousand fold. BOPHY 3a can be used as a pH probe.

A New Water-Soluble Phosphorus-Dipyrromethene and Phosphorus-Azadipyrromethene Dye: PODIPY/aza-PODIPY

PODIPY and aza-PODIPY have been successfully prepared by the treatment of dipyrromethene and azadipyrromethene with POCl3 in the presence of Et3 N. The new PODIPY and aza-PODIPY dyes are found to have photophysical properties. PODIPY and aza-PODIPY are water-soluble, and aza-PODIPY is suited for labeling living Hep-2 cells for imaging assays in the near-infrared region. Molecular orbital calculations show that the increase in the HOMO-LUMO band gap for the lowest energy absorption bands is observed in the new phosphorus-containing aza-PODIPY, and the HOMO and LUMO energies of aza-PODIPY are found to be higher than those of aza-BODIPY.

A styryl-containing aza-BODIPY as a near-infrared dye

A novel styryl-containing pyrrole was developed by the reaction of E-4-phenylbut-3-en-2-one with 3-phenyl-2H-azirine in the presence of LDA. Utilizing this pyrrole, asymmetric styryl-containing aza-BODIPYs have been prepared in the NIR region as a result of the combined extension of conjugation. This styryl-containing aza-BODIPY was bright enough to be suited to label living cells for imaging assays in the NIR region.

Singlet oxygen generation properties of isometrically dibromated thienyl-containing aza-BODIPYs

Isometrically dibromated thienyl-containing aza-BODIPYs CDB-1 and BDB-2 with potential use as photosensitizers (PSs) were successfully prepared and their photophysical properties were fully characterized. Singlet oxygen generation experiments were also performed. In this regard, PS CDB-1 was found to be more effective and had about two-fold rate enhancement compared to PS BDB-2. DFT and TD-DFT calculations helped to provide insights into the distinct intersystem crossing (ISC) processes observed for CDB-1 and BDB-2.

Novel soluble poly(ether imide)s with trifluoromethyl and chloride pendant groups for optical materials

A new bis(ether dianhydride) monomer [4,4′-(2-(3′-trifluoromethyl-4′-chlorophenyl)-1,4-phenylenedioxy)-diphthalic anhydride (3)] was designed and prepared through a multistep reaction sequence. The new monomer 3 was polymerized with typical diamines, such as PDA, ODA, APB, 6FAPB and 9F–Cl-APB, using a two-step chemical imidization method to obtain the corresponding poly(ether imide)s (PEIs) (4a–4e). All the PEIs had high glass transition temperatures, excellent thermal stability, good solubility, and could be made into transparent and flexible films. The cast films showed UV-vis absorption edges at 346–369 nm, low birefringences of 0.0052–0.0131, low dielectric constants of 2.69–2.80, and low water uptakes of 0.30–0.52 wt%. Based on the characterization results, a series of optical materials with tunable refractive indices were obtained by copolymerization in the range of 1.6217–1.5523 at 650 nm.

Organocatalytic sulfa-Michael/aldol cascade: constructing functionalized 2,5-dihydrothiophenes bearing a quaternary carbon stereocenter

A practical sulfa-Michael/aldol cascade reaction of 1,4-dithiane-2,5-diol and α-aryl-β-nitroacrylates has been developed, which allows efficient access to functionalized 2,5-dihydrothiophenes bearing a quaternary carbon stereocenter in moderate to good yields with high enantioselectivities.