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There is a great demand to measure protein-ligand interactions in rapid and low cost way. Here, we developed a microfluidic droplet-based thermal shift assay (dTSA) system for high-throughput screening of small-molecule protein ligands. The system is composed of a nanoliter droplet array chip, a microfluidic droplet robot, and a real-time fluorescence detection system. Total 324 assays could be performed in parallel in a single chip with an 18 x 18 droplet array. The consumption of dTSA for each protein or ligand sample was only 5 nL (femtomole scale), which is significantly reduced by over 3 orders of magnitude compared with those in 96- or 384-well plate-based systems. We also observed the implementation of TSA in nanoliter droplet format could substantially improve assay precision with relative standard deviation (RSD) of 0.2% (n = 50), which can be ascribed to the enhanced thermal conduction in small volume reactors. The dTSA system was optimized by studying the effect of droplet volumes, as well as protein and fluorescent dye (SYPRO Orange) concentrations. To demonstrate its potential in drug discovery, we applied the dTSA system in screening inhibitors of human thrombin with a commercial library containing 100 different small molecule compounds, and two inhibitors were successfully identified and confirmed. [ABSTRACT FROM AUTHOR]

The linear bis-cyclometalated Ru(II) complex [(ttpy)Ru(ttabp)Ru(ttpy)]2+was prepared from the oxidative coupling of the monometalliccomplex [(ttpy)Ru(dtab)]+in good yield, where ttpy is4′-tolyl-2,2′:6′,2″-terpyridine, ttabpis 3,3′,5,5′-tetrakis(1-butyl-1H-1,2,3-triazol-4-yl)biphenyl,and dtab is 1,3-bis(1-butyl-1H-1,2,3-triazol-4-yl)benzene.The electronic properties of these two complexes were studied andcompared by electrochemical and spectroscopic methods and DFT/TDDFTcalculations. The complex [(ttpy)Ru(ttabp)Ru(ttpy)]2+showedtwo consecutive RuII/IIIredox waves at +0.34 and +0.51V vs Ag/AgCl with a comproportionation constant Kcof 760. One-electron oxidation of [(ttpy)Ru(ttabp)Ru(ttpy)]2+by electrochemical methods produced the mixed-valent complex[(ttpy)Ru(ttabp)Ru(ttpy)]3+, which exhibited a symmetricintervalence charge transfer band at 1800 nm (νmax= 5550 cm–1, εmax= 5100 M–1cm–1, Δν1/2= 3580 cm–1). The energy and shape of this bandare very similar in the different solvents studied (CH3CN, DMF, CH2Cl2). [(ttpy)Ru(ttabp)Ru(ttpy)]3+was determined to be a class II/III borderline system withthe electronic coupling parameter Hab=530 cm–1. It displayed a metal-centered rhombicEPR signal at 77 K with an isotropic gfactor of2.109 and total ganisotropy of 0.256, which pointsto an appreciable spin distribution on the bridging ligand in additionto the metal centers. [ABSTRACT FROM AUTHOR]

A series of asymmetrical bis-tridentate cyclometalated complexes including [Ru(Mebib)(Mebip)]+, [Ru(Mebip)(dpb)]+, [Ru(Mebip)(Medpb)]+, and [Ru(Mebib)(tpy)]+ and two bis-tridentate noncyclometalated complexes [Ru(Mebip)2]2+ and [Ru(Mebip)(tpy)]2+ were prepared and characterized, where Mebib is bis(N-methylbenzimidazolyl)benzene, Mebip is bis(N-methylbenzimidazolyl)pyridine, dpb is 1,3-di-2-pyridylbenzene, Medpb is 4,6-dimethyl-1,3-di-2-pyridylbenzene, and tpy is 2,2′:6′,2″-terpyridine. The solid-state structure of [Ru(Mebip)(Medpb)]+ is studied by X-ray crystallographic analysis. The electrochemical and spectroscopic properties of these ruthenium complexes were studied and compared with those of known complexes [Ru(tpy)(dpb)]+ and [Ru(tpy)2]2+. The change of the supporting ligands and coordination environment allows progressive modulation of the metal-associated redox potentials (RuII/III) from +0.26 to +1.32 V vs Ag/AgCl. The introduction of a ruthenium cyclometalated bond in these complexes results in a significant negative potential shift. The RuII/III potentials of these complexes were analyzed on the basis of Lever’s electrochemical parameters (EL). Density functional theory (DFT) and time-dependent DFT calculations were carried out to elucidate the electronic structures and spectroscopic spectra of complexes with Mebib or Mebip ligands. [ABSTRACT FROM AUTHOR]

A new bridging ligand 1,3,6,8-tetrakis(1-butyl-1H-1,2,3-triazol-4-yl)pyrene (ttapyr) was designed and synthesized by "click" chemistry. This ligand was used to construct a linear dimetallic biscyclometalated Ru(II) complex [(tpy)Ru(ttapyr)Ru(tpy)]2+ and a monometallic complex [(tpy)Ru(ttapyr)]+, where tpy is 2,2′:62′,22″-terpyridine. The electronic properties of these complexes were studied and compared by electrochemical and spectroscopic methods with the aid of DFT calculations. One-electron oxidation of [(tpy)Ru(ttapyr)Ru(tpy)]2+ with cerium ammonium nitrate produced a mixed-valent complex [(tpy)Ru(ttapyr)Ru(tpy)]3+. The intramolecular electronic coupling between individual metal centers was quantified by the intervalence charge transfer transition analysis. Mixed-valent complex [(tpy)Ru(ttapyr)Ru(tpy)]3+ exhibits a metal-centered rhombic EPR signal at 77 K with an average g factor of 2.203. [ABSTRACT FROM AUTHOR]

A tridentate cyclometalating ligand, 1,3-di(1,2,3-triazol-4-yl)benzene (dtab), has been prepared and used for the syntheses of a number of cyclometalated RuIIcomplexes. A comparison of the electrochemical and spectroscopic properties of cyclometalated complexes made from dtab or 1,3-di(2-pyridyl)benzene is presented as well. [ABSTRACT FROM AUTHOR]

A novel iron-catalyzed intermolecular decarboxylative Csp3−Csp2coupling reaction using proline derivatives as starting materials is developed. In this process, a series of potentially useful ligands (tertiary aminonaphthol) for catalysis was obtained. [ABSTRACT FROM AUTHOR]

Cyclometalated diruthenium complexes 1(PF6)2–5(PF6)2 bridged by 1,3,6,8-tetra(pyrid-2-yl)-pyrene have been prepared, with the terminal ligand bis(N-methylbenzimidazolyl)pyridine (1(PF6)2), 4′-di-(p-methoxyphenyl)amino-2,2′:6′,2″-terpyridine (2(PF6)2), 4′-p-methoxyphenyl-2,2′:6′,2″-terpyridine (3(PF6)2), 2,2′:6′,2″-terpyridine (4(PF6)2), and trimethyl-4,4′,4″-tricarboxylate-2,2′:6′,2″-terpyridine (5(PF6)2). The single-crystal X-ray structure of 4(PF6)2 is presented. These complexes show two stepwise anodic redox pairs, and the potentials progressively increase from 1(PF6)2 to 5(PF6)2. Complexes 1(PF6)2–4(PF6)2 have comparable electrochemical potential splitting of 200–210 mV, while complex 5(PF6)2 has a splitting of 170 mV. Upon one-electron oxidation by chemical oxidation or electrolysis, the resulting mixed-valent complexes 13+–53+ display broad and intense absorptions between 1000 and 3000 nm. Complexes 13+ and 23+ show the presence of a higher-energy shoulder band in addition to the main near-infrared absorption band. This shoulder band is less distinguished for 33+–53+. Three-state theory has been used to explain this difference. The one-electron oxidized forms, 13+–53+, exhibit rhombic EPR signals at 77 K with the isotropic g values in the range of 2.18–2.24. Density functional theory (DFT) and time-dependent DFT (TDDFT) computations have been performed on 12+–52+ to characterize their electronic structures and rationalize the absorption spectra in a wide energy range. DFT computations on 13+–53+ show that both ruthenium ions and the bridging ligand have comparable spin densities. TDDFT computations on 13+ and 43+ have been performed to complement the experimental results. [ABSTRACT FROM AUTHOR]

In this work, five novel 2D isostructural Cd(II)-lanthanide(III) heterometallic-organic frameworks [CdCl(L)EuxTby(H2O)(DMA)](NO3)·3DMA (IFMC-36-EuxTby: x = 1, y = 0, IFMC-36-Eu; x = 0.6, y = 0.4, IFMC-36-Eu0.6Tb0.4; x = 0.5, y = 0.5, IFMC-36-Eu0.5Tb0.5; x = 0.4, y = 0.6, IFMC-36-Eu0.4Tb0.6; x = 0, y = 1, IFMC-36-Tb; H3L is 4,4',4"-((2,2',2"-(nitrilotris(methylene))tris(1H-benzo[d]imidazole-2,1-diyl))tris(methylene))tribenzoic acid; IFMC = Institute of Functional Material Chemistry) have been successfully synthesized by taking advantage of different molar ratios of lanthanide(III) (Ln(III)) and metalloligands under solvothermal conditions. Further luminescent measurements indicate that IFMC-36-EuxTby exhibits characteristic sharp emission bands of Eu(III) and Tb(III), and the intensities of red and green can be modulated correspondingly by tuning the ratios of Eu(III) and Tb(III). Particularly, the solvent-dependent luminescent behavior of IFMC-36-Eu shows a potential application in detection of small-molecule pollutant nitrobenzene by significant fluorescence quenching. Furthermore, IFMC-36-Eu displays preeminent anti-interference ability and could be used for sensing in the systems with complicated components. This is the first time that a d-f heterometallic-organic framework can be investigated as a chemical sensor for selective, sensitive, and recyclable detection of nitrobenzene. [ABSTRACT FROM AUTHOR]

In this contribution, we devote our effort to explore the effect of stoichiometry of the 4,4′-dipyridylsulfide (dps) ligand on the final structures in the ZnII-hfipbb binary system (H2hfipbb = 4,4′-(hexafluoroisopropylidene)bis(benzoic acid)). The solvothermal reaction of zinc acetate and H2hfipbb with the different stoichiometries of dps from 0.1 to 0.4 mmol has resulted in three new coordination polymers, [Zn(hfipbb)(H2hfipbb)0.5]n(1) and [Zn2(hfipbb)2(dps)(H2O)]n(2aand 2b). The structure determination reveals that complex 1displays a three-dimensional (3D) 2-fold parallel interpenetrating pillared-layer network with one-dimensional double left- and right-handed helical tubes. Complexes 2aand 2bare framework-isomeric as two unusual (3,4)-connected 3D coordination networks, i.e., a 4-nodal (7·82)(4·7·9)(72·84)(4·72·8·92) net and 2-fold interpenetrating (83)2(85·10) net. In addition, the properties of thermogravimetric analysis, X-ray powder diffraction, and photoluminescent behaviors of the complexes have been also discussed. [ABSTRACT FROM AUTHOR]