Highly insulating alkane rings with destructive σ-interference

Science China Chemistry - Destructive quantum interference (DQI) provides a unique approach to controlling the leakage current in the OFF state of molecular devices. However, the DQI in...     

Amino-Acid-Induced Circular Polarized Luminescence in One-Dimensional Manganese(II) Halide Hybrid

Circular polarized luminescence (CPL)-active materials attract great attentions owing to their widely applications in 3D optical displays and encrypted transmission. Inspired by the strategies adopted in perovskite based CPL materials, herein, CPL-active hybrids (D)- and (L)-(tert-butyl prolinate)MnCl₃ were successfully prepared by assembling chiral D/L tert-butyl prolinate with manganese (II) chloride. Single crystal structures show the as-formed hybrids possess one-dimensional (1D) structure containing linear chains of face-sharing MnCl₆ octahedral surrounded by prolinate cations. The 1D Mn(II) hybrids display strong red emission peaked at 646 nm with PLQY of 67.1 % and 57.2 % for d -type and l -type, respectively, representing the highest PLQY for 1D Mn^II hybrids. Interestingly, the 1D Mn(II) hybrids exhibit prominent circular dichroism (CD) signals and remarkable CPL activity with the dissymmetry factor g of 6.1*10⁻³ and −6.3*10⁻³ from 550 to 800 nm for (D)- and (L)-(tert-butyl prolinate)MnCl₃, respectively, owing to the existence of chiral cations. It is worthy noted the obtained g represents the highest value for non-lead organic–inorganic hybrids.     

Density of lithium fluoride—lithium carbonate-based molten salts

The density of the LiF-Li₂CO₃ melts system was measured using the Archimedean method. Using the quadratic regression orthogonal design with two factors, a regression equation for the density of LiF-Li₂CO₃ melts was obtained in which the concentration of LiF and temperature were considered. The results indicated that the density of the LiF-Li₂CO₃ melts decreased with either increasing the concentration of LiF or increasing temperature; a linear relation was observed between density and temperature. In addition, the influences of NaF, KF, NaCl, and KCl additives on the densities of the given systems were studied. The addition of NaF and KF increased the density of the melts, whereas NaCl and KCl resulted in an initial increase and subsequent decrease with an increasing additive concentration. The density attained a maximum at NaCl and KCl mass fraction of approximately 15%.     

Crystal Structure of a 4-Methyl-phenylacetylide-bridged Pt~IICu~I_2 Heterotrinuclear Organometallic Complex

1 INTRODUCTION Over the past decades, metal alkynyl complexes have attracted more and more attention due to their potential applications in conducting polymers, lumi- nescent materials and supramolecular chemis- try[1～10]. Compared to the rapid growth o…     

Synthesis and Crystal Structure of a Tetranuclear Silver Complex with Bis（diphenylphosphino） amine-dioxide as a Tridentate Ligand

1 INTRODUCTION The coordination chemistry of the nitrogen-contai- ning diphosphine ligand bis(diphenylphosphino)ami- ne (Ph2PNHPPh2) has recently received much atten- tion because the P atoms can bridge metal centers in μ-bonding mode to form bi- or polynuclear complex- es[1~10]. It has been shown that the acidity of N–H proton would promote functionalization on the ligand backbone[4, 5, 11]. Although a few complexes contain- ing deprotonated tridentate Ph2PNPPh2 have been synthesi…     

Assembly of a supramolecular cube, [(Cp*WS3Cu3)8 Cl8(CN)12Li4] from a preformed incomplete cubane-like compound [PPh4][Cp*WS3(CuCN)3

A supramolecular cube has been formed by linking WS3Cu3 clusters with bidentate ligands. Eight WS3Cu3 clusters, which have an incomplete cubane-like structure, serve as the three connecting nodes of the cube, while 12 bridging cyanide anions coordinated to copper centers lie along the edges of the cube. Eight chloride anions and four lithium cations are located inside the cube.     

Preparation,structures, and redox and emission characteristics of the isothiocyanate complexes of hexarhenium(III) clusters [Re6(mu3-E)8(NCS)6]4- (E = S,Se)

Hexarhenium(III) complexes with terminal isothiocyanate ligands, [(n-C(4)H(9))(4)N](4)[Re(6)(mu(3)-S)(8)(NCS)(6)] (1) and (L)(4)[Re(6)(mu(3)-Se)(8)(NCS)(6)] (L(+) = PPN(+) (2a), (n-C(4)H(9))(4)N(+) (2b)), have been prepared by three different methods. Complex 1 was prepared by the reaction of [(n-C(4)H(9))(4)N](4)[Re(6)(mu(3)-S)(8)Cl(6)] with molten KSCN at 200 degrees C, while 2b was obtained by refluxing the chlorobenzene-DMF (2:1 v/v) solution of [Re(6)(mu(3)-Se)(8)(CH(3)CN)(6)](SbF(6))(2) and [(n-C(4)H(9))(4)N]SCN. The [Re(6)(mu(3)-Se)(8)(NCS)(6)](4)(-) anion was also obtained from a mixture of Cs(2)[Re(6)(mu(3)-Se)(8)Br(4)] and KSCN in C(2)H(5)OH by a mechanochemical activation at room temperature for 20 h and isolated as 2a. The X-ray structures of 1 and 2a.4DMF have been determined (1, C(70)H(144)N(10)S(14)Re(6), monoclinic, space group P2(1)/n (No. 14), a = 14.464(7) A, b = 22.059(6) A, c = 16.642(8) A, beta = 113.62(3) degrees, V = 4864(3) A(3), Z = 2; 2a.4DMF, C(162)H(144)N(14)O(4)P(8)S(6)Se(8)Re(6), triclinic, space group P1 (No. 2), a = 15.263(2) A, b = 16.429(2) A, c = 17.111(3) A, alpha = 84.07(1) degrees, beta = 84.95(1) degrees, gamma = 74.21(1) degrees, V = 4098.3(8) A(3), Z = 1). All the NCS(-) ligands in both complexes are coordinated to the metal center via nitrogen site with the Re-N distances in the range of 2.07-2.13 A. The redox potentials of the reversible Re(III)(6)/Re(III)(5)Re(IV) process in acetonitrile are +0.84 and +0.70 V vs. Ag/AgCl for [Re(6)(mu(3)-S)(8)(NCS)(6)](4)(-) and [Re(6)(mu(3)-Se)(8)(NCS)(6)](4)(-), respectively, which are the most positive among the known hexarhenium complexes with six terminal anionic ligands. The complexes show strong red luminescence with the emission maxima (lambda(max)/nm), lifetimes (tau(em)/micros), and quantum yields (phi(em)) being 745 and 715, 10.4 and 11.8, and 0.091 and 0.15 for 1 and 2b, respectively, in acetonitrile. The data reasonably well fit in the energy-gap plots of other hexarhenium(III) complexes. The temperature dependence of the emission spectra and tau(em) of 1 and [(n-C(4)H(9))(4)N](4)[Re(6)(mu(3)-S)(8)Cl(6)] are also reported.     

Syntheses, characterization and redox properties of oxo-centred triruthenium cluster dimers and trimers linked by ortho-metallated polypyridyl ligands

A series of mono-, di- and trimeric oxo-centred triruthenium cluster compounds with ortho-metallated polypyridyl ligands were prepared by reaction of oxo-centred triruthenium precursor compound [Ru3O(OAc)6(py)2(CH3OH)]+ (1) with bis(2,2'-bipyridin-5-yl)butadiyne (bpyC[triple bond, length as m-dash]C-C[triple bond, length as m-dash]Cbpy), bis(2,2'-bipridin-5-yl)ethyne (bpyC[triple bond, length as m-dash]Cbpy), 2,2'-bipyrazine (bpz), pyrazino[2,3-f]quinoxaline (pyq), or 4,7-phenanthroline (4,7-phen). As revealed by redox wave splitting, electronic interactions are operating between two Ru3O redox centres in most of the triruthenium cluster dimers and trimers. The cluster-cluster interactions are highly sensitive to the variations in bonding modes of the polypyridyl ligands. Ortho-metallation of the bridging ligand induces an enhanced electronic interaction between two triruthenium centres.     

Conformation changes and luminescent properties of Au-Ln (Ln = Nd, Eu, Er, Yb) arrays with 5-ethynyl-2,2'-bipyridine

Reaction of polymeric gold(I) acetylide species (bpyC[triple bond]CAu)n (bpyC[triple bond]CH = 5-ethynyl-2,2'-bipyridine) with diphosphine ligands Ph2P(CH2)nPPh2 (n = 2-6) or 1,1'-bis(diphenylphosphino)-ferrocene (dppf) in dichloromethane induces isolation of binuclear gold(I) complexes (bpyC[triple bond]CAu)2{mu-Ph2P(CH2)nPPh2} or (bpyC[triple bond]CAu)2(mu-dppf). Complexation of Ln(hfac)3 (hfac = hexafluoroacetylacetonate, Ln = Nd, Eu, Er, Yb) subunits to the binuclear gold(I) complexes through 2,2'-bipyridyl chelation gives the corresponding Au4Ln4 or Au2Ln2 heteropolynuclear complexes. Noticeably, upon formation of the Au4Ln4 arrays by complexation of (bpyC[triple bond]CAu)2(mu-Ph2P(CH2)4PPh2) (3) with Ln(hfac)3 units, trans-conformation in 3 transforms dramatically to the cis-arranged form due to the strong driving force from ligand-unsupported Au-Au contacts between two Au2Ln2 subunits. In contrast, cis-conformation in (bpyC[triple bond]CAu)2(mu-dppf) (6) stabilized by Au-Au interactions is reversed to the trans-oriented form upon formation of Au2Ln2 arrays by introducing Ln(hfac)3 units through 2,2-bipyridyl chelation. The binuclear gold(I) complexes show bright blue luminescence featured by ligand-centered pi --> pi* (C[triple bond]Cbpy) states together with low-energy emission at 500-540 nm, associated with 3(pi-->pi*) excited states, mixed probably with some characteristic from (Au-Au) --> (C[triple bond]Cbpy) 3MMLCT transition. For Au4Ln4 or Au2Ln2 complexes, sensitized lanthanide luminescence is achieved by energy transfer from Au-acetylide chromophores with lifetimes in the sub-millisecond range for EuIII complexes, whereas in the microsecond range for near-infrared emitting NdIII, ErIII, and YbIII species.     

Luminescent heteronuclear Au(I)5Ag(I)8 complexes of [1,2,3-C6(C6H4R-4)3]3- (R = H, CH3, But) by cyclotrimerization of arylacetylides

Unusual AuI-AgI heterometallic complexes [Au5Ag8(mu-dppm)4{1,2,3-C6(C6H4R-4)3}(CCC6H4R-4)7]3+ (R = H 1, CH3 2, But 3) were isolated by reactions of polymeric silver arylacetylides (AgCCC6H4R-4)n with binuclear gold component [Au2(mu-dppm)2(MeCN)2]2+ (dppm = bis(diphenylphosphino)methane), in which cyclotrimerization of arylacetylide -CCC6H4R-4 affords trianion {1,2,3-C6(C6H4R-4)3}3- with an unprecedented mu5-bonding mode. Compounds 1(SbF6)3-3(SbF6)3 exhibit intense photoluminescence derived from an MLCT (Au5Ag8 --> CCC6H4R-4) transition, mixed with a metal cluster-centered excited states.