A New Potent Inhibitor of Glycogen Phosphorylase Reveals the Basicity of the Catalytic Site.

The design and synthesis of a glucose-based acridone derivative (GLAC), a potent inhibitor of glycogen phosphorylase (GP) are described. GLAC is the first inhibitor of glycogen phosphorylase, the electronic absorption properties of which are clearly distinguishable from those of the enzyme. This allows probing subtle interactions in the catalytic site.

Luminescent Cyclometalated Platinum Complexes with π-Bonded Catecholate Organometallic Ligands.

A series of cyclometalated platinum(II) complexes of the type [(ppy)Pt(L)] (n = 0, 1) with π-bonded catecholates acting as organometallic ligands (L) have been prepared and characterized by analytical techniques. In addition, the structures of two complexes of the series were determined by single-crystal X-ray diffraction. The packing shows the formation of a 1D supramolecular assembly generated by d-π interactions among individual units.

Induced phosphorescence from Pt → Ag and Ag(i)...Ag(i) metallophilic interactions in benzenedithiolatodiimine-Pt2/Ag2 clusters: a combined experimental and theoretical investigation.

We report the synthesis and luminescence properties of a novel platinum(ii)-silver(i) cluster exhibiting supramolecular donor-acceptor dative Pt → Ag bonds as well as d(10)...

Surface induces different crystal structures in a room temperature switchable spin crossover compound.

We investigated the influence of surfaces in the formation of different crystal structures of a spin crossover compound, namely [Fe(L)2] (LH: (2-(pyrazol-1-yl)-6-(1H-tetrazol-5-yl)pyridine), which is a neutral compound thermally switchable around room temperature. We observed that the surface induces the formation of two different crystal structures, which exhibit opposite spin transitions, i.e.

Tuning excited states of bipyridyl platinum(II) chromophores with π-bonded catecholate organometallic ligands: synthesis, structures, TD-DFT calculations, and photophysical properties.

A series of bipyridyl (bpy) Pt(II) complexes with π-bonded catecholate (cat) [(bpy)Pt(LM)][BF4]n (2-5) (LM = Cp*Rh(cat), n = 2; Cp*Ir(cat), n = 2; Cp*Ru(cat), n = 1; and (C6H6)Ru(cat), n = 2) were prepared and fully characterized. The molecular structures of the four compounds were determined and showed that the solid-state packing is different and dependent on the π-bonded catecholate unit. For instance, while the (bpy)Pt(II) complexes 2 and 3 with rhodium and iridium catecholates did not show any Pt···Pt interactions those with the ruthenium catecholates 4 and 5 showed the presence of Pt···Pt and π-π interactions among individual units and generated one- and two-dimensional supramolecular chains.

Spirobifluorene bridged Ir(III) and Os(II) polypyridyl arrays: synthesis, photophysical characterization, and energy transfer dynamics.

The synthesis, characterization, photophysics, and time-dependent density functional theory (TD-DFT) calculations of spirobifluorene-bipyridine based iridium(III), osmium(II), and mixed Ir/Os complexes are presented. The preparation of the reference and mixed complexes proceeded step-by-step and microwave irradiation facilitated the complexation of osmium. The absorption of the target heterobimetallic derivative, Ir-L-Os, is described by linear combination of half of the absorption spectra of the homobimetallic analogues, Ir-L-Ir and Os-L-Os, due to the occurrence of mixed ligand and metal based transitions when the spirobifluorene-(bpy)(2) bridging ligand L is linked to the metal, confirming a negligible interaction between the substituted metallic chromophores.

Turning on red and near-infrared phosphorescence in octahedral complexes with metalated quinones.

We report the synthesis of π-bonded ruthenium, rhodium, and iridium o-benzoquinones [Cp*M(o-C(6)H(4)O(2))](n) [M = Ru (2), n = 1-; Rh (3), n = 0; Ir (4), n = 0] following a novel synthetic procedure. Compounds 2-4 were fully characterized by spectroscopic methods and used as chelating organometallic linkers, "OM-linkers", toward luminophore bricks such as Ru(bpy)(2)(2+), Rh(ppy)(2)(+), and Ir(ppy)(2)(+) (bpy = 2,2'-bipyridine; ppy = 2-phenylpyridine) for the design of a novel family of octahedral bimetallic complexes of the general formula [(L-L)(2)M(OM-linkers)][X](m) (X = counteranion; m = 0, 1, 2) whose luminescent properties depend on the choice of the OM-linker and the luminophore brick. Thus, dinuclear assemblies such as [(bpy)(2)Ru(2)][OTf] (5-OTf), [(bpy)(2)Ru(2)][Δ-TRISPHAT] (5-ΔT) {TRISPHAT = tris[tetrachlorobenzene-1,2-bis(olato)]phosphate}, [(bpy)(2)Ru(3)][OTf](2) (6-OTf), [(bpy)(2)Ru(4)][OTf](2) (7-OTf), [(bpy)(2)Ru(4)][Δ-TRISPHAT](2) (7-ΔT), [(ppy)(2)Rh(2)] (8), [(ppy)(2)Rh(3)][OTf] (9-OTf), [(ppy)(2)Rh(4)][OTf] (10-OTf), [(ppy)(2)Rh(4)][Δ-TRISPHAT] (10-ΔT), [(ppy)(2)Ir(2)] (11), [(ppy)(2)Ir(3)][OTf] (12-OTf), [(ppy)(2)Ir(4)][OTf] (13-OTf), and [(ppy)(2)Ir(4)][Δ-TRISPHAT] (13-ΔT) were prepared and fully characterized.

Camptothecin and thiocamptothecin: the role of sulfur in shifting the hydrolysis equilibrium towards the closed lactone form.

Adverse effects have limited the clinical potential of 20-(S)-camptothecin (CPT) and led to a growing interest in the development of CPT analogues that exhibit less severe drawbacks, while maintaining their therapeutic activity. Recently, a thiopyridone isostere of CPT, 20-(S)-thiocamptothecin (TCPT), was developed that resulted more potent than the parent compound in H460, HT29 and IGROV-1 cell lines. The improved activity of TCPT over CPT might be due to the greater stability of the lactone ring.

Organometallic quinonoid linkers: a versatile tether for the design of panchromatic ruthenium(II) heteroleptic complexes.

The synthesis, X-ray structure determination, and photophysical investigation of a novel series of heteroleptic ruthenium(II) polypyridine complexes with organometallic linkers are reported. The displayed panchromatic absorption features are assigned by means of time-dependent density functional theory studies.

1,10-Phenanthrolines with tunable luminescence upon protonation: a spectroscopic and computational study.

We have synthesized nine 2,9-aryl-substituted 1,10-phenanthrolines (1-9) with the aim of rationalizing their electronic absorption and luminescence properties in both the basic and acid form. The latter are generated upon addition of trifluoroacetic acid to CH2Cl2 solutions of 1-9 and their formation is unambiguously evidenced by UV-vis absorption and 1H NMR spectroscopy. 1-9 can be subdivided into three groups, depending on their chemical structure and luminescence behavior.

The electron transfer rate of large TPA based compounds: a joint theoretical and electrochemical approach.

A series of triphenylamine (TPA) based compounds is investigated by means of density functional theory and cyclic voltammetry. Using the Nicholson's formalism, the measured deltaE(p) are correlated with B3LYP/6-31G* calculated reorganisation energies (lambda), elucidating the trend followed by the electron transfer rate of these compounds. Besides the direct dependency upon the dimension of the cationic fragment contributing to the hole stabilisation, the lambdas are tuned by the symmetry local to the TPA units, as evidenced by the structural relaxation of the cations.