Yu-Chun Chen

Iridium-complex-functionalized Fe3O4/SiO2 core/shell nanoparticles: a facile three-in-one system in magnetic resonance imaging, luminescence imaging, and photodynamic therapy.

Highly uniform Fe3O4/SiO2 core/shell nanoparticles functionalized by phosphorescent iridium complexes (Ir) have been strategically designed and synthesized. The Fe3O4/SiO2(Ir) nanocomposite demonstrates its versatility in various applications: the magnetic core provides the capability for magnetic resonance imaging and the great enhancement of the spin-orbit coupling in the iridium complex makes it well suited for phosphorescent labeling and simultaneous singlet oxygen generation to induce apoptosis.

Rational reductive fusion of two heterometallic clusters: formation of a highly stable, intensely phosphorescent Au–Ag aggregate and application in two-photon imaging in human mesenchymal stem cells

An unprecedented Au-Ag alkynyl-diphosphine aggregate, obtained via CO-reduction of a mixture of simple reagents, exhibits intense room-temperature phosphorescence free from O(2) quenching, and serves as an excellent phosphorescence dye suited for both one- and two-photon imaging in human stem cells.

Mercury(II) recognition and fluorescence imaging in vitro through a 3D-complexation structure.

8,8-(1,4,10,13-Tetrathia-7,16-diazacyclooctadecane-7,16-diyl)-bis(methylene)diquinolin-7-ol (TTBQ) was synthesized and proved to selectively recognize Hg(2+), forming a Hg(2+)/TTBQ complex with an association constant (K(a)) as large as approximately 1.3 x 10(4) +/- 520 M(-1) in aqueous solution. Single crystals of TTBQ and a TTBQ-Hg(2+) complex have also been successfully grown, in which the latter unambiguously revealed a cagelike configuration consisting of thiol-crown and dual 7-hydroxyquinoline moieties to firmly trap Hg(2+). This 3D-complexation structure accounts for approximately 25-fold luminescence enhancement and a detection limit of sub-microM in water for sensing Hg(2+). Great selectivity toward Hg(2+) has been exhibited over alkali- and alkaline-earth metal ions, first-row transition-metal ions, and other cations studied. This chemosensor is particularly suited for the detection of Hg(2+) in a pH range of 5.5 to 7.5. This, in combination with its fine biocompatibility, leads to the success toward in vitro mercury recognition based on fluorescence imaging.

Homogenous, far-reaching tuning and highly emissive QD–silica core–shell nanocomposite synthesized via a delay photoactive procedure; their applications in two-photon imaging of human mesenchymal stem cells

In this article, we present the exploration of a facile synthetic tactic incorporating delay-photo-oxidation to recover the loss in emission frequently encountered after encapsulating quantum dots (QDs) inside a silica shell. This facile synthesis procedure reproducibly increases emissive intensity of QDs (core)–SiO2 (shell) (60 nm) nanomaterials by >5 fold (QY from 3% to >15%). The resulting QDs (core)–SiO2 proved to be a single quantum dot in single SiO2, homogeneous and highly monodispered; their emissions have been successfully fine-tuned from visible to the near infrared region. We then demonstrate their power in biological imaging by labeling human mesenchymal stem cells under two-photon confocal microscopy. The results of low cytotoxicity, efficient labeling, and specific location nearby the nucleus characters of these nanoparticles should spark an intensive relevant research within a living system.

Photoisomerization of a Maleonitrile‐Type Salen Schiff Base and Its Application in Fine‐Tuning Infinite Coordination Polymers

Strategically designed salen ligand 2,3-bis[4-(di-p-tolylamino)-2-hydroxybenzylideneamino]maleonitrile (1), which has pronounced excited-state charge-transfer properties, shows a previously unrecognized form of photoisomerization. On electronic excitation (denoted by an asterisk), 1Z*-->1E isomerization takes place by rotation about the C2--C3 bond, which takes on single-bond character due to the charge-transfer reaction. The isomerization takes place nonadiabatically from the excited-state (1Z) to the ground-state (1E) potential-energy surface in the singlet manifold; 1Z and 1E are neither thermally inconvertible at ambient temperature (25-30 degrees C), nor does photoinduced reverse 1E*-->1Z (or 1Z*) isomerization occur. Isomers 1Z and 1E show very different coordination chemistry towards a Zn(II) precursor. More prominent coordination chemistry is evidenced by a derivative of 1 bearing a carboxyl group, namely, N,N-dicyanoethenebis(salicylideneimine)dicarboxylic acid (2). Applying 2Z and its photoinduced isomer 2E as building blocks, we then demonstrate remarkable differences in morphology (sphere- and needlelike nanostructure, respectively) of their infinite coordination polymers with Zn(II).

CCDC 745791: Experimental Crystal Structure Determination

Related Article: I.O.Koshevoy, Yi-Chih Lin, Yu-Chun Chen, A.J.Karttunen, M.Haukka, Pi-Tai Chou, S.P.Tunik, T.Pakkanen|2010|Chem.Commun.|46|1440|doi:10.1039/b920001k