Chemistry

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Two new chromophores in the format, donor-acceptor-donor, have been synthesized in high yields from easily available starting materials. These compounds do not show any two-photon absorption (TPA) cross-section in the wavelength range, 780-900 nm when probed by the Z-scan technique with a femtosecond laser. However, in presence of Zn(II), Ca(II) or Mg(II) ion, each compound gives exceptionally large TPA cross-section in the same wavelength range. © 2008 Elsevier B.V. All rights reserved.

(SoNS) School of Natural Sciences

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Journal of Luminescence

Acyclic donor-acceptor-donor chromophores for large enhancement of two-photon absorption cross-section in the presence of Mg(II), Ca(II) or Zn(II) ions

The first BODIPY library (BD) was synthesized, and a highly selective glucagon sensor, Glucagon Yellow (BD-105), was discovered by fluorescence image-based screening method. BD library was synthesized via a Knoevenagel-type condensation reaction with 160 benzaldehydes and the 1,3 dimethyl-BODIPY scaffold. Using BD compounds, a fluorescence image-based screening was performed against three cell lines including AlphaTC1 and BetaTC6 cells which secret glucagon and insulin, respectively, and HeLa as control cells. Out of the 160 candidate probes, one compound, Glucagon Yellow, exhibited selective staining only in AlphaTC1 cells. The selectivity of Glucagon Yellow toward glucagon was confirmed in vitro by comparison of its fluorescence intensity change against 19 biologically relevant analytes. Subsequent immunostaining experiments revealed that Glucagon Yellow and the glucagon antibody colocalized in pancreas tissue, showing a high quantitative correlation analysis by the Pearson's coefficient constant (Rr ) 0.950). These results demonstrated the potential application of Glucagon Yellow as a glucagon imaging agent in live cells and tissues. © 2009 American Chemical Society.

Journal of the American Chemical Society

Synthesis of a BODIPY library and its application to the development of live cell glucagon imaging probe

The design and two-component [2 + 3] self-assembly of a series of new organometallic molecular prisms (3a-d) are described. Assemblies 3a,b incorporate 4,4',4'-tris[ethynyl-trans-Pt(PEt2)2(N0 3)]triphenylamine (la) containing a Pt-ethynyl functionality as tritopic planar acceptor and organic "clips" 2a and 2b, respectively [where 2a = l,3-bis(3-pyridyl)isophthalic amide; 2b = l,3-bis(ethynyl3-pyridyl) benzene]. In a complementary approach an organic tritopic planar donor ligand 2c [2c = 4,4',4'-tris(4-pyridylethynyl)triphenylamine] was assembled with an organometallic "clip", 1,8-bis[{trans-Pt(PEt3) 2(N03)}ethynyl]anthracene (lb), to obtain prism 3c. A new organometallic carboncentered acceptor, l,l,l-tris[4-{trans-Pt(PEt 3)2(N03)}ethynylphenyl]ethane (1c), has been prepared and its prism derivative (3d) using an organic "clip" is prepared. Assemblies (3a-d) were characterized by multinuclear NMR spectroscopy, electrospray ionization mass spectroscopy and elemental analysis. 3a-d showed fluorescence behavior in solution and quenching of fluorescence intensity (3a, 3c-d) was noticed upon addition of TNT (2,4,6-trinitrotoluene), a common constituent of many commercial explosives. A thin film of the assembly 3d made by spin coating of a solution of 3x 10-5 M in DMF on a 1 cm 2 quartz plate showed fluorescence response to the vapor of TNT. Copy; 2009 American Chemical Society.

Organometallics

Self-Assembly of molecular prisms via Pt3 organometallic acceptors and a Pt2 organometallic clip

Two new neutral copper-azido polymers [Cu3(N3) 6(tmen)2]n (1) and [Cu6(N 3)12(deen)2]n (2) [tmen = N,N,N,N -tetramethylethylenediamine and deen = N,N-diethylethylenediamine] have been synthesized by using lower molar equivalents of the chelating diamine ligands with Cu(NO3)2 {\textperiodcentered} 3H2O and an excess of NaN3. The single crystal X-ray structure shows that in the basic unit of the 1D complex 1, the three Cu" ions are linked by double end-on azido bridges with CU-NEO-CU angles on both sides of the magnetic exchange critical angle of 108°. Complex 2 is a 3D framework of a basic Cu6 cluster. Cryomagnetic susceptibility measurements over a wide range of temperature exhibit dominant ferromagnetic behavior in both the complexes. Density functional theory calculations (B3LYP functional) have been performed on the trinuclear unit to provide a qualitative theoretical interpretation of the overall ferromagnetic behavior shown by the complex 1. {\textcopyright}2009 American Chemical Society.

Inorganic Chemistry

CuII-azide polymers of Cu3 and Cu6 building units: Synthesis, structures and magnetic exchange mechanism

Two azine molecules, [3-{4-(dimethylamino)phenyl}prop-2-en-1-ylidene] hydrazone (HL) and [4-(dimethylamino)benzylidene]hydrazone (LL) synthesized via Schiff base condensation, show an absorption band due to intra-ligand charge transfer (ILCT). Both ligands show weak emission in the absence of a metal ion as input. When Ag+ ions are added to either compound in THF, the metal ion gets bonded to the azine moiety resulting in a high intensity emission (∼400 fold). While Cu+ shows a slight enhancement of emission, other first-row transition, alkali or alkaline-earth metal ions do not show any emission allowing Ag+ ions to be detected in the presence of these metal ions. Both the Ag+ complexes were characterised by X-ray crystallography and show solid-state spectra similar to their solution spectra. Time-resolved fluorescence measurements done on the complexes show two excited-state lifetimes. © The Royal Society of Chemistry 2009.

Fulltext

Dalton Transactions

Ag(i) induced emission with azines having donor-acceptor-donor chromophore

To expand the diversity of 1,3,5-triazine libraries to aryl and alkyl functionalities through the CC bond, we employed a novel orthogonal synthesis via Grignard monoalkylation or monoarylation of cyanuric chloride in solution to prepare aryl- or alkyl-substituted triazine building blocks. These aryl- or alkyl-substituted triazine building blocks were captured by a resin-bound amine, followed by amination and acidic cleavage with high purity. Herein, we demonstrate a novel orthogonal synthesis of a tagged aryl- and alkyl-triazine library on solid support, utilizing building blocks prepared via Grignard reaction in solution. Through incorporation of a triethylene glycol linker at one of the alternate sites on the triazine scaffold we explored an intrinsic tagged library approach. © CSIRO 2009.

Australian Journal of Chemistry

Novel orthogonal synthesis of a tagged combinatorial triazine library via grignard reaction

A convenient approach for the synthesis of a methyl analogue of crispine A, a potent anticancer agent, through intramolecular Schmidt reaction of azido-ketone 6 is described. {\textcopyright} 2007 Elsevier Ltd. All rights reserved.

Tetrahedron Letters

An intramolecular Schmidt reaction strategy for the synthesis of a methyl analogue of crispine A

Bridging the domains of cheminformatics and bioinformatics in the post-genomic era requires the convergence of goals, tools, techniques and annotations. This article reviews recent research at the interface of the domains that shows evidence of this convergence. While graph theoretical representations have long been used to develop simple topological descriptions of molecules, graph theory-based network concepts are also widely employed in systems biology. Shape and conformation are important for understanding intermolecular interactions, and several structure-based cheminformatic descriptors have been developed and applied to drug-like molecules and biomolecules. Data fusion methods and shared ontologies can also help integrate data from multiple sources in order to generate a holistic picture of the shared molecular informatics domain. © The Thomson Corporation.

Current Opinion in Drug Discovery and Development

Bioinformatics and cheminformatics: Where do the twain meet?

Two different coumarin derivatives have been connected via an imine linkage to obtain a new fluorescence signaling system. This compound itself does not show any emission due to rapid isomerization around the C=N bond. However, in the presence of a Mg(II) ion, this isomerization is stopped because of bonding to the metal ion resulting in high-intensity (∼550-fold) emission. Other metal ions like Li(I), Ca(II), and Zn(II) show very little emission, while biologically relevant transition-metal ions do not show any emission. In this way, the Mg(II) ion can be detected in the presence of these ions. © 2008 American Chemical Society.

A coumarin-derived fluorescence probe selective for magnesium

Anisotropic displacement parameters (ADPs) are compared for H atoms estimated using three recently described procedures, both among themselves and with neutron diffraction results. The results convincingly demonstrate that all methods are capable of giving excellent results for several benchmark systems and identify systematic discrepancies for several atom types. A revised and extended library of internal H-atom mean-square displacements is presented for use with Madsen's SHADE web server [J. Appl. Cryst. (2006), 39, 757-758; http://shade.ki.ku.dk], and the improvement over the original SHADE results is substantial, suggesting that this is now the most readily and widely applicable of the three approximate procedures. Using this new library - SHADE2 - it is shown that, in line with expectations, a segmented rigid-body description of the heavy atoms yields only a small improvement in the agreement with neutron results. The SHADE2 library, now incorporated in the SHADE web server, is recommended as a routine procedure for deriving estimates of H-atom ADPs suitable for use in charge-density studies on molecular crystals, and its widespread use should reveal remaining deficiencies and perhaps overcome the inherent bias in the majority of such studies. © International Union of Crystallography 2008.