Replacing AgTSSCH2‐R with AgTSO2C‐R in EGaIn‐Based Tunneling Junctions Does Not Significantly Change Rates of Charge Transport

This paper compares rates of charge transport by tunneling across junctions with the structures Ag^TSX(CH₂)_2nCH₃ //Ga₂O₃ /EGaIn (n=1–8 and X= ? SCH₂? and ? O₂C? ); here Ag^TS is template‐stripped silver, and EGaIn is the eutectic alloy of gallium and indium. Its objective was to compare the tunneling decay coefficient (β, Å^?1) and the injection current (J₀, A cm^?2) of the junctions comprising SAMs of n‐alkanethiolates and n‐alkanoates. Replacing Ag^TSSCH₂‐R with Ag^TSO₂C‐R (R=alkyl chains) had no significant influence on J₀ (ca. 3×10³ A cm^?2) or β (0.75–0.79 Å^?1)—an indication that such changes (both structural and electronic) in the Ag^TSXR interface do not influence the rate of charge transport. A comparison of junctions comprising oligo(phenylene)carboxylates and n‐alkanoates showed, as expected, that β for aliphatic (0.79 Å^?1) and aromatic (0.60 Å^?1) SAMs differed significantly.     

Synthese und Kristallstruktur des Fluorid‐ino‐Oxosilicats Cs2YFSi4O10

Synthesis and Crystal Structure of the Fluoride ino‐Oxosilicate Cs₂YFSi₄O₁₀ The novel fluoride oxosilicate Cs₂YFSi₄O₁₀ could be synthesized by the reaction of Y₂O₃, YF₃ and SiO₂ in the stoichiometric ratio 2 : 5 : 3 with an excess of CsF as fluxing agent in gastight sealed platinum ampoules within seventeen days at 700 °C. Single crystals of Cs₂YFSi₄O₁₀ appear as colourless, transparent and water‐resistant needles. The characteristic building unit of Cs₂YFSi₄O₁₀ (orthorhombic, Pnma (no. 62), a = 2239.75(9), b = 884.52(4), c = 1198.61(5) pm; Z = 8) comprises infinite tubular chains of vertex‐condensed [SiO₄]^4? tetrahedra along [010] consisting of eight‐membered half‐open cube shaped silicate cages. The four crystallographically different Si⁴⁺ cations all reside in general sites 8d with Si–O distances from 157 to 165 pm. Because of the rigid structure of this oxosilicate chain the bridging Si–O–Si angles vary extremely between 128 and 167°. The crystallographically unique Y³⁺ cation (in general site 8d as well) is surrounded by four O^2? and two F^? anions (d(Y–O) = 221–225 pm, d(Y–F) = 222 pm). These slightly distorted trans‐[YO₄F₂]^7? octahedra are linked via both apical F^? anions by vertex‐sharing to infinite chains along [010] (?(Y–F–Y) = 169°, ?(F–Y–F) = 177°). Each of these chains connects via terminal O^2? anions to three neighbouring oxosilicate chains to build up a corner‐shared, three‐dimensional framework. The resulting hexagonal and octagonal channels along [010] are occupied by the four crystallographically different Cs⁺ cations being ten‐, twelve‐, thirteen‐ and fourteenfold coordinated by O^2? and F^? anions (viz.[(Cs1)O₁₀]^19?, [(Cs2)O₁₀F₂]^21?, [(Cs3)O₁₂F]^24?, and [(Cs4)O₁₂F₂]^25? with d(Cs–O) = 309–390 pm and d(Cs–F) = 360–371 pm, respectively).     

Counter‐Anion‐Regulated Mixed‐Valency of Cobalt(II/III) Centers in a Metallosupramolecular Framework

A diamagnetic Au^I₄Co^III₂ hexanuclear complex, [Au₄Co₂(dppe)₂(l ‐nmc)₄]²⁺ ([ 1_{L ‐ nmc} ]²⁺; dppe=1,2‐bis(diphenylphosphino)ethane, l ‐H₂nmc=N‐methyl‐l ‐cysteine), was newly synthesized by the reaction of [Co(l ‐nmc)₂]^? with [Au₂Cl₂(dppe)] and crystallized with different inorganic anions (X=ClO₄^?, NO₃^?, Cl^?, SO₄^2?) to produce ionic solids ([ 1_{L ‐ nmc} ]X_n). Single‐crystal X‐ray analysis revealed that all the solids crystallize in the chiral space group F432 with a face‐centered‐cubic lattice structure consisting of supramolecular octahedra of complex cations. The paramagnetic nature of all the solids was evidenced by magnetic susceptibility measurements, showing the variation of the oxidation states of two cobalt centers in [ 1_{L ‐ nmc} ]ⁿ⁺ from Co^II_1.00Co^III_1.00 for X=ClO₄^? or NO₃^? to Co^II_0.67Co^III_1.33 for X=Cl^?, via Co^II_0.83Co^III_1.17 for X=SO₄^2?. The difference in the Co^II/III mixed‐valences was explained by the difference in sizes and charges of counter anions accommodated in lattice interstices with a fixed volume.     

Synthesis and Characterization of an Unexpected Asymmetric Binuclear Copper（Ⅰ） Complex Containing 4-Vinyl-pyridine

The asymmetric binuclear copper(I) complex [Cu₂(dppm)₂(C₇H₇N)(μ‐HCOO)](NO₃) (dppm=Ph₂PCH₂PPh₂, C₇H₇N=4‐vinyl‐pyridine) has been prepared and characterized by physicochemical and spectroscopic methods. The complex is photoluminescent at room temperature. It crystallizes in triclinic system, space group P‐1 with a= 1.2719(3) nm, b=1.8637(4) nm, c=1.1656(2) nm, a=97.16(3)°, β= 104.94(3)″, γ=89.39(3)°, V=2.648.1(9) nm³, D_c= 1.390 g.m^?3, Z=2, μ=0.974 mm^?1, R=0.0483 for 5716 independently observed reflections with I>2δ(I). The structure consists of [Cu₂(dppm)₂(C₇H₇N)(μ‐HCOO)]⁺cations and nitrate anions. The copper atoms show different coordination modes: Cu(1) displays a distorted trigonal and Cu(2) a tetrahedred geometry.     

The Structural Systematics of Protonation of Some Important Nitrogen‐base Ligands. II. Some Univalent Anion Salts of Singly Protonated Bis(2‐pyridyl)amine

Syntheses and single crystal X‐ray structure determinations are recorded for a number of normal and ‘acid’ salts of bis(2‐pyridylamine), ‘dpa’, with univalent anions, X, variously hydrated, i.e. [dpaH]X·nH₂O, and [dpaH]X·HX·nH₂O. The ‘normal’ salt arrays so characterized are for X = Br^? (n = 2, isomorphous with the previously described chloride compound) and, I^?, ClO₄^?, ‘tca^?’ (≡ Cl₃CCO₂)^? (all n = 1); acid salt arrays are described for X = NO₃^? and tca (both n = 0). In all cases except those of X = ClO₄^?, NO₃^?, there is one independent formula unit devoid of crystallographic symmetry comprising the asymmetric unit of the structure. In all cases, the proton associated with the cation is ‘chelated’ by the pair of ring nitrogen atoms, disposed ‘endo’; in the tca adducts and the nitrate salt, the total cation is disordered in each case by inversion about a real or putative inversion centre between the rings. In the perchlorate compound, the (ordered) cation lies on a crystallographic 2‐axis, as does the water molecule, and the perchlorate ion, which is disordered about such an axis; in the nitrate compound, the acid hydrogen atom is modelled as disposed on a crystallographic inversion centre between a pair of symmetry‐related nitrate groups, containing, like the Htca adduct, the [XHX]^? moiety rather than a diprotonated cation.     

Thermochromic Luminescent Nest‐Like Silver Thiolate Cluster

A novel discrete open high‐nuclearity nest‐like silver thiolate cluster complex, [Ag₃₃S₃(StBu)₁₆(CF₃COO)₉(NO₃)(CH₃CN)₂](NO₃) ( 1 ), has been isolated with nitrate and S^2? anions acting as structure‐directing templates. Its similar nest‐like structure has been assembled into an extended layer [Ag₃₁S₃(StBu)₁₆(NO₃)₉]_n ( 2 ) by adjustment of auxiliary ligand. More interestingly, both complexes exhibit temperature‐dependent luminescence of high sensitivity with a large fluorescence enhancement (12‐fold for 1 , 21‐fold for 2 ), which can be easily recognized by the naked‐eye (dramatic red‐shift Δ=104 nm for 1 , larger Δ=113 nm for 2 at 77 K compared to those at 298 K). The correlation between luminescent thermochromism and temperature‐dependent variation of the coordination modes of template NO₃^? anion, Ag???S and Ag???Ag distances are also elucidated through variable‐temperature single‐crystal X‐ray crystal structure (VT‐SCXRD) analyses.     

斯蒂芬酸氢铷的制备，晶体结构和热分解机理

A new compound,[RbHTNR]_∞[HTNR:C_6H(NO_2)_3(OH)O],was synthesized by the reaction of rubidium ni-trate and styphnic acid.The molecular structure was characterized using X-ray diffraction analysis,elementalanalysis and FTIR spectroscopy.The crystalline is monoclinic with space group P2_1/n and the empirical formulaC_6H_2N_3O_8Rb.The unit cell parameters are:a=0.4525 nm,b=1.0777 nm,c=1.9834 nm,β=90.47(2)°,V=0.96725 nm~3,Z=4,D_c=2.263 g/cm~3,Mr=329.58,F(000)=640,μ(Mo Kα)=5.165 mm~(-1).The thermal decompo-sition mechanism of the complex was studied by differential scanning calorimetry(DSC),thermogravimetry-derivative thermogravimetry(TG-DTG)and FTIR techniques.At the linear rate of 10 ℃/min,the thermaldecomposition of the complex showed three mass reducing processes between 60 and 500 ℃,and finally evolvedRbCN and some gaseous products.     

Synthesis and characterization of di‐n‐butyltin(IV) complexes with 4′/2′‐nitrobiphenyl‐2‐carboxylic acids: X‐ray crystal structures of [{(n‐C4H9)2Sn(OCOC12H8NO2−4′)}2O]2 and (n‐C4H9)2Sn{OCOC12H8NO2−4′}2

Reactions of di‐n‐butyltin(IV) oxide with 4′/2′‐nitrobiphenyl‐2‐carboxylic acids in 1 : 1 and 1 : 2 stoichiometry yield complexes [{(n‐C₄H₉)₂Sn(OCOC₁₂H₈NO₂?4′/2′)}₂O]₂ ( 1 and 2 ) and (n‐C₄H₉)₂Sn(OCOC₁₂H₈NO₂?4′/2′)₂ ( 3 and 4 ) respectively. These compounds were characterized by elemental analysis, IR and NMR (¹H, ¹³C and ¹¹⁹Sn) spectroscopy. The IR spectra of these compounds indicate the presence of anisobidentate carboxylate groups and non‐linear C? Sn? C bonds. From the chemical shifts δ (¹¹⁹Sn) and the coupling constants ¹J(¹³C, ¹¹⁹Sn), the coordination number of the tin atom and the geometry of its coordination sphere have been suggested. [{(n‐C₄H₉)₂Sn(OCOC₁₂H₈NO₂?4′)}₂O]₂ ( 1 ) exhibits a dimeric structure containing distannoxane units with two types of tin atom with essentially identical geometry. To a first approximation, the tin atoms appear to be pentacoordinated with distorted trigonal bipyramidal geometry. However, each type of tin atom is further subjected to a sixth weaker interaction and may be described as having a capped trigonal bipyramidal structure. The diffraction study of the complex (n‐C₄H₉)₂Sn(OCOC₁₂H₈NO₂?4′)₂ ( 3 ) shows a six–coordinate tin in a distorted octahedral frame containing bidentate asymmetric chelating carboxylate groups, with the n‐Bu groups trans to each other. The n‐Bu? Sn? n‐Bu angle is 152.8° and the Sn? O distances are 2.108(4) and 2.493(5) Å. The oxygen atom of the nitro group of the ligand does not participate in bonding to the tin atom in 1 and 3 . Crystals of 1 are triclinic with space group P1 and of that of 3 have orthorhombic space group Pnna. Copyright © 2003 John Wiley & Sons, Ltd.     

Anion‐Directed Copper(II) Metallocages,Coordination Chain,and Complex Double Salt: Structures,Magnetic Properties,EPR Spectra,and Density Functional Study

A series of Cu^II metallo‐assemblies showing anion‐directed structural variations, including five metallocages [(G^n?)?{Cu₂(Hdpma)₄}]^(8?n)+(A^?)_8?n (G^n?=NO₃^?, ClO₄^?, SiF₆^2?, BF₄^?, SO₄^2?; A^?=NO₃^?, ClO₄^?, BF₄^?, CH₃SO₄^?; Hdpma=bis(3‐pyridylmethyl)ammonium cation), a complex double salt, namely, (H₃dpma)₄(CuCl₄)₅Cl₂, and a coordination chain, namely, [Cu₂(dpma)(OAc)₄], are reported. The influence of the anion can be explained by its coordinating ability, the affinity of which for the Cu^II center interferes significantly with metallocage formation, and its shape, which offers host–guest recognition ability to engage in weak metal–anion coordination and hydrogen bonding to the organic ligand, which are responsible for metallocage templation. EPR studies of these metallocages in the powder phase at room temperature and 77 K showed a trend of the g values (g_||>2.10>g_⊥>2.00) indicating a ‐based ground state with square‐pyramidal geometry for the Cu^II centers. The magnetism of these metallocages can be interpreted as the result of a combination of relatively small magnetic coupling integrals and a substantial contribution of temperature‐independent paramagnetism (TIP). The weak magnetic interaction is corroborated by the results of DFT calculations and the EPR spectra. Availability of the low‐lying state for spin population was confirmed by a magnetization study, which revealed a magnetic moment approaching 2Nβ, which would explain the presence of the larger TIP term.     

Two C3‐Symmetric Dy3III Complexes with Triple Di‐μ‐methoxo‐μ‐phenoxo Bridges,Magnetic Ground State,and Single‐Molecule Magnetic Behavior

Two series of isostructural C₃‐symmetric Ln₃ complexes Ln₃ ? [BPh₄] and Ln₃ ? 0.33[Ln(NO₃)₆] (in which Ln^III=Gd and Dy) have been prepared from an amino‐bis(phenol) ligand. X‐ray studies reveal that Ln^III ions are connected by one μ₂‐phenoxo and two μ₃‐methoxo bridges, thus leading to a hexagonal bipyramidal Ln₃O₅ bridging core in which Ln^III ions exhibit a biaugmented trigonal‐prismatic geometry. Magnetic susceptibility studies and ab initio complete active space self‐consistent field (CASSCF) calculations indicate that the magnetic coupling between the Dy^III ions, which possess a high axial anisotropy in the ground state, is very weakly antiferromagnetic and mainly dipolar in nature. To reduce the electronic repulsion from the coordinating oxygen atom with the shortest Dy?O distance, the local magnetic moments are oriented almost perpendicular to the Dy₃ plane, thus leading to a paramagnetic ground state. CASSCF plus restricted active space state interaction (RASSI) calculations also show that the ground and first excited state of the Dy^III ions are separated by approximately 150 and 177 cm^?1, for Dy₃ ? [BPh₄] and Dy₃ ? 0.33[Dy(NO₃)₆], respectively. As expected for these large energy gaps, Dy₃ ? [BPh₄] and Dy₃ ? 0.33[Dy(NO₃)₆] exhibit, under zero direct‐current (dc) field, thermally activated slow relaxation of the magnetization, which overlap with a quantum tunneling relaxation process. Under an applied H_dc field of 1000 Oe, Dy₃ ? [BPh₄] exhibits two thermally activated processes with U_eff values of 34.7 and 19.5 cm^?1, whereas Dy₃ ? 0.33[Dy(NO₃)₆] shows only one activated process with U_eff=19.5 cm^?1.     

Time‐Resolved Assembly of Cluster‐in‐Cluster {Ag12}‐in‐{W76} Polyoxometalates under Supramolecular Control

We report the time‐resolved supramolecular assembly of a series of nanoscale polyoxometalate clusters (from the same one‐pot reaction) of the form: [H_(10+m)Ag₁₈Cl(Te₃W₃₈O₁₃₄)₂]_n, where n=1 and m=0 for compound 1 (after 4 days), n=2 and m=3 for compound 2 (after 10 days), and n=∞ and m=5 for compound 3 (after 14 days). The reaction is based upon the self‐organization of two {Te₃W₃₈} units around a single chloride template and the formation of a {Ag₁₂} cluster, giving a {Ag₁₂}‐in‐{W₇₆} cluster‐in‐cluster in compound 1 , which further aggregates to cluster compounds 2 and 3 by supramolecular Ag‐POM interactions. The proposed mechanism for the formation of the clusters has been studied by ESI‐MS. Further, control experiments demonstrate the crucial role that TeO₃^2?, Cl^?, and Ag⁺ play in the self‐assembly of compounds 1 – 3 .     

Water‐Free Rare‐Earth‐Metal Ionic Liquids/Ionic Liquid Crystals Based on Hexanitratolanthanate(III) Anion

The hexanitratolanthanate anion (La(NO₃)₆^3?) is an interesting symmetric anion suitable to construct the component of water‐free rare‐earth‐metal ionic liquids. The syntheses and structural characterization of eleven lanthanum nitrate complexes, [C_nmim]₃[La(NO₃)₆] (n=1, 2, 4, 6, 8, 12, 14, 16, 18), including 1,3‐dimethylimidazolium hexanitratolanthanate ([C₁mim]₃[La(NO₃)₆], 1 ), 1‐ethyl‐3‐methylimidazolium hexanitratolanthanate ([C₂mim]₃[La(NO₃)₆], 2 ), 1‐butyl‐3‐methylimidazolium hexanitratolanthanate ([C₄mim]₃[La(NO₃)₆], 3 ), 1‐isobutyl‐3‐methylimidazolium hexanetratolanthanate ([isoC₄mim]₃[La(NO₃)₆], 4 ), 1‐methyl‐3‐(3′‐methylbutyl)imidazolium hexanitratolanthanate ([MC₄mim]₃[La(NO₃)₆], 5 ), 1‐hexyl‐3‐methylimidazolium hexanitratolanthanate ([C₆mim]₃[La(NO₃)₆], 6 ), 1‐methyl‐3‐octylimidazolium hexanitratolanthanate ([C₈mim]₃[La(NO₃)₆], 7 ), 1‐dodecyl‐3‐methylimidazolium hexanitratolanthanate ([C₁₂mim]₃[La(NO₃)₆], 8 ), 1‐methyl‐3‐tetradecylimidazolium hexanitratolanthanate ([C₁₄mim]₃[La‐(NO₃)₆], 9 ), 1‐hexadecyl‐3‐methylimid‐azolium hexanitratolanthanum ([C₁₆dmim]₃[La(NO₃)₆], 10 ), and 1‐methyl‐3‐octadecylimidazolium hexanitratolanthanate ([C₁₈mim]₃[La(NO₃)₆], 11 ) are reported. All new compounds were characterized by ¹H and ¹³C NMR, and IR spectroscopy as well as elemental analysis. The crystal structure of compound 1 was determined by using single‐crystal X‐ray diffraction, giving the following crystallographic information: monoclinic; P2₁/c; a=15.3170 (3), b=14.2340 (2), c=13.8954(2) Å; β=94.3453(15)°, V=3020.80(9) ų, Z=4, ρ=1.764 g cm^?3. The coordination polyhedron around the lanthanum ion is rationalized by six nitrate anions with twelve oxygen atoms. No hydrogen‐bonding network or water molecule was found in 1 . The thermodynamic stability of the new complexes was investigated by using thermogravimetric analysis (TGA). The water‐free hexanitratolanthanate ionic liquids are thermal and moisture stable. Four complexes, namely complexes 8 – 11 , were found to be ionic liquid crystals by differential scanning calorimetry (DSC) and polarizing optical microscopy (POM). They all present smectic A liquid‐crystalline phase.     

Small‐Molecule Anion Recognition by a Shape‐Responsive Bowl‐Type Dodecavanadate

A dodecavanadate, [V₁₂O₃₂]⁴⁻, is an inorganic bowl‐type host with a cavity entrance with a diameter of 4.4 Å in the optimized structure. Linear, bent, and trigonal planar anions are tested as guest anions and the formation of host–guest complexes, [V₁₂O₃₂(X)]⁵⁻ (X=CN⁻, OCN⁻, NO₂⁻, NO₃⁻, HCO₂⁻, and CH₃CO₂⁻), were confirmed by X‐ray crystallographic analyses and a ⁵¹V NMR spectroscopy study. The degree of distortion of the bowl from a regular to an oval shape depends on the type of guest anion. In ⁵¹V NMR spectroscopy, all chemical shifts of the host–guest complexes are clearly shifted after guest incorporation. The incorporation reaction rates for OCN⁻, NO₂⁻, HCO₂⁻, and CH₃CO₂⁻ are much larger than those of NO₃⁻ and halides. The incorporated nonspherical molecular anions in the dodecavanadate host are easily dissociated or exchanged for other anions, whereas spherical halides in the host are preserved without dissociation, even in the presence of the tested anions.     

Borromean‐Entanglement‐Driven Assembly of Porous Molecular Architectures with Anion‐Modified Pore Space

A series of metal–organic frameworks based on a flexible, highly charged Bpybc ligand, namely 1? Mn?OH^?, 2? Mn?SO₄^2?, 3? Mn?bdc^2?, 4? Eu?SO₄^2? (H₂BpybcCl₂=1,1′‐bis(4‐carboxybenzyl)‐4,4′‐bipyridinium dichloride, H₂bdc=1,4‐benzenedicarboxylic acid) have been obtained by a self‐assembly process. Single‐crystal X‐ray‐diffraction analysis revealed that all of these compounds contained the same n‐fold 2D→3D Borromean‐entangled topology with irregular butterfly‐like pore channels that were parallel to the Borromean sheets. These structures were highly tolerant towards various metal ions (from divalent transition metals to trivalent lanthanide ions) and anion species (from small inorganic anions to bulky organic anions), which demonstrated the superstability of these Borromean linkages. This non‐interpenetrated entanglement represents a new way of increasing the stability of the porous frameworks. The introduction of bipyridinium molecules into the porous frameworks led to the formation of cationic surface, which showed high affinities to methanol and water vapor. The distinct adsorption and desorption isotherms of methanol vapor in four complexes revealed that the accommodated anion species (of different size, shape, and location) provided a unique platform to tune the environment of the pore space. Measurements of the adsorption of various organic vapors onto framework 1? Mn?OH^? further revealed that these pores have a high adsorption selectivity towards molecules with different sizes, polarities, or π‐conjugated structures.     

Centimeter‐Sized Single Crystal of Two‐Dimensional Halide Perovskites Incorporating Straight‐Chain Symmetric Diammonium Ion for X‐Ray Detection

Two‐dimensional (2D) AA′_n?1M_nX_3n+1 type halide perovskites incorporating straight‐chain symmetric diammonium cations define a new type of structure, but their optoelectronic properties are largely unexplored. Reported here is the synthesis of a centimeter‐sized AA′_n?1M_nX_3n+1 type perovskite, BDAPbI₄ (BDA=NH₃C₄H₈NH₃), single crystal and its charge‐transport properties under X‐ray excitation. The crystal shows a staggered configuration of the [PbI₆]^4? layers, a band gap of 2.37 eV, and a low trap density of 3.1×10⁹ cm^?3. The single‐crystal X‐ray detector exhibits an excellent sensitivity of 242 μC Gy_air^?1 cm^?2 under the 10 V bias (0.31 V μm^?1), a detection limit as low as 430 nGy_air s^?1, ultrastable response current, a stable baseline with the lowest dark current drift of 6.06×10^?9 nA cm^?1 s^?1 V^?1, and rapid response time of τ_rise=7.3 ms and τ_fall=22.5 ms. These crystals are promising candidates for the next generation of optoelectronic devices.     

Synthesis,Crystal Structure and Thermochemical Properties of a One‐Dimensional Chain Complex [Cd(succ)PIP]n

A new complex, [Cd(succ)PIP]_n (PIP=2‐phenyl‐imidazo[4,5‐f]1,10‐phenanthroline, H₂‐succ=succinate), was synthesized and characterized by X‐ray crystallography, elemental analysis, and TG‐DTG. The results show that the complex crystallizes in an orthorhombic space group Pcca; a=14.065(2) Å, b=9.901(8) Å, c=28.933(2) Å and Z=8. The structure of the complex is one‐dimensional chain [Cd(succ)PIP]_n, and each Cd²⁺ is five‐coordinated by two chelating nitrogen atoms from one PIP ligand, three oxygen atoms from three different succ dianionic ligands to form a distorted trigonal‐bipyramida geometry. The constant‐volume combustion energy of the complex, Δ_cU, was determined by an intelligent micro‐rotating‐bomb calorimeter (IMRBC‐type I) at 298.15 K. Then the standard molar enthalpy of combustion, Δ_cH_m^?, and the standard molar enthalpy of formation, Δ_fH_m^? have been calculated.     

Ligand‐to‐Ligand Charge‐Transfer Transitions of Platinum(II) Complexes with Arylacetylide Ligands with Different Chain Lengths: Spectroscopic Characterization,Effect of Molecular Conformations,and Density Functional Theory Calculations

The complexes [Pt(tBu₃tpy){C?C(C₆H₄C?C)_n?1R}]⁺ (n=1: R=alkyl and aryl (Ar); n=1–3: R=phenyl (Ph) or Ph‐N(CH₃)₂‐4; n=1 and 2, R=Ph‐NH₂‐4; tBu₃tpy=4,4’,4’’‐tri‐tert‐butyl‐2,2’:6’,2’’‐terpyridine) and [Pt(Cl₃tpy)(C?CR)]⁺ (R=tert‐butyl (tBu), Ph, 9,9’‐dibutylfluorene, 9,9’‐dibutyl‐7‐dimethyl‐amine‐fluorene; Cl₃tpy=4,4’,4’’‐trichloro‐2,2’:6’,2’’‐terpyridine) were prepared. The effects of substituent(s) on the terpyridine (tpy) and acetylide ligands and chain length of arylacetylide ligands on the absorption and emission spectra were examined. Resonance Raman (RR) spectra of [Pt(tBu₃tpy)(C?CR)]⁺ (R=n‐butyl, Ph, and C₆H₄‐OCH₃‐4) obtained in acetonitrile at 298 K reveal that the structural distortion of the C?C bond in the electronic excited state obtained by 502.9 nm excitation is substantially larger than that obtained by 416 nm excitation. Density functional theory (DFT) and time‐dependent DFT (TDDFT) calculations on [Pt(H₃tpy)(C?CR)]⁺ (R= n‐propyl (nPr), 2‐pyridyl (Py)), [Pt(H₃tpy){C?C(C₆H₄C?C)_n?1Ph}]⁺ (n=1–3), and [Pt(H₃tpy){C?C(C₆H₄C?C)_n?1C₆H₄‐N(CH₃)₂‐4}]⁺/+H⁺ (n=1–3; H₃tpy=nonsubstituted terpyridine) at two different conformations were performed, namely, with the phenyl rings of the arylacetylide ligands coplanar (“cop”) with and perpendicular (“per”) to the H₃tpy ligand. Combining the experimental data and calculated results, the two lowest energy absorption peak maxima, λ₁ and λ₂, of [Pt(Y₃tpy)(C?CR)]⁺ (Y=tBu or Cl, R=aryl) are attributed to ¹[π(C?CR)→π*(Y₃tpy)] in the “cop” conformation and mixed ¹[d_π(Pt)→π*(Y₃tpy)]/¹[π(C?CR)→π*(Y₃tpy)] transitions in the “per” conformation. The lowest energy absorption peak λ₁ for [Pt(tBu₃tpy){C?C(C₆H₄C?C)_n?1C₆H₄‐H‐4}]⁺ (n=1–3) shows a redshift with increasing chain length. However, for [Pt(tBu₃tpy){C?C(C6H4C?C)_n?1C₆H₄‐N(CH₃)₂‐4}]⁺ (n=1–3), λ₁ shows a blueshift with increasing chain length n, but shows a redshift after the addition of acid. The emissions of [Pt(Y₃tpy)(C?CR)]⁺ (Y=tBu or Cl) at 524–642 nm measured in dichloromethane at 298 K are assigned to the ³[π(C?CAr)→π*(Y₃tpy)] excited states and mixed ³[d_π(Pt)→π*(Y₃tpy)]/³[π(C?C)→π*(Y₃tpy)] excited states for R=aryl and alkyl groups, respectively. [Pt(tBu₃tpy){C?C(C₆H₄C?C)_n?1C₆H₄‐N(CH₃)₂‐4}]⁺ (n=1 and 2) are nonemissive, and this is attributed to the small energy gap between the singlet ground state (S₀) and the lowest triplet excited state (T₁).     

La3OCl[AsO3]2: Ein Lanthan‐Oxidchlorid‐Oxoarsenat(III) mit “lone‐pair”‐Kanalstruktur

La₃OCl[AsO₃]₂: A Lanthanum Oxide Chloride Oxoarsenate(III) with a “Lone‐Pair” Channel Structure La₃OCl[AsO₃]₂ was prepared by the solid‐state reaction between La₂O₃ and As₂O₃ using LaCl₃ and CsCl as fluxing agents in evacuated silica ampoules at 850 °C. The colourless crystals with pillar‐shaped habit crystallize tetragonally (a = 1299.96(9), c = 558.37(5) pm, c/a = 0.430) in the space group P4₂/mnm (no. 136) with four formula units per unit cell. The crystal structure contains two crystallographically different La³⁺ cations. (La1)³⁺ is coordinated by six oxygen atoms and two chloride anions in the shape of a bicapped trigonal prism (CN = 8), whereas (La2)³⁺ carries eight oxygen atoms and one Cl^? anion arranged in the shape of tricapped trigonal prism (CN = 9). The isolated pyramidal [AsO₃]^3? anions (d(As–O) = 175–179 pm) consist of three oxygen atoms (O2 and two O3), which surround the As³⁺ cations together with the free, non‐binding electron pair (lone pair) Ψ¹‐tetrahedrally (?(O–As–O) = 95°, 3×). One of the three crystallographically independent oxygen atoms (O1), however, is exclusively coordinated by four (La2)³⁺ cations in the shape of a real tetrahedron (d(O–La) = 236 pm, 4×). These [(O1)(La2)₄]¹⁰⁺ tetrahedra form endless chains in the direction of the c axis through trans‐edge condensation. Empty channels, constituted by the lone‐pair electrons of the Cl^? anions and the As³⁺ cations in the Ψ¹‐tetrahedral oxoarsenate(III) anions [AsO₃]^3?, run parallel to [001] as well.     

Enhancement of TbIII–CuII Single‐Molecule Magnet Performance through Structural Modification

We report a series of 3d–4f complexes {Ln₂Cu₃(H₃L)₂X_n} (X=OAc^?, Ln=Gd, Tb or X=NO₃^?, Ln=Gd, Tb, Dy, Ho, Er) using the 2,2′‐(propane‐1,3‐diyldiimino)bis[2‐(hydroxylmethyl)propane‐1,3‐diol] (H₆L) pro‐ligand. All complexes, except that in which Ln=Gd, show slow magnetic relaxation in zero applied dc field. A remarkable improvement of the energy barrier to reorientation of the magnetisation in the {Tb₂Cu₃(H₃L)₂X_n} complexes is seen by changing the auxiliary ligands (X=OAc^? for NO₃^?). This leads to the largest reported relaxation barrier in zero applied dc field for a Tb/Cu‐based single‐molecule magnet. Ab initio CASSCF calculations performed on mononuclear Tb^III models are employed to understand the increase in energy barrier and the calculations suggest that the difference stems from a change in the Tb^III coordination environment (C_4v versus C_s).     

Hexanuclear 3d − 4f metal–organic cages assembled from a carboxylic acid‐functionalized tris‐triazamacrocycle for highly selective fluorescent sensing of picric acid

Two Ln^III ions are sandwiched by dinuclear Co^II building blocks derived from a tris‐triazamacrocyclic ligand bearing pendant carboxylic acid functionality, 1,3,5‐tris((4,7‐bis(2‐carboxyethyl)‐1,4,7‐triazacyclonon‐1‐yl)methyl)‐benzene (H₆L), giving rising to two nanoscale heterometallic metal–organic cages formulated as [Co₄Ln₂(LH_2.5)₂(H₂O)₄]·(ClO₄)₆·NO₃·nH₂O [Ln = Dy, n = 12 ( 1 ); Ln = Yb, n = 9 ( 2 )], whose internal cavity accommodates a guest NO₃^? anion. Their hexanuclear cage‐like architectures are maintained both in solution and solid states as confirmed by mass spectrum as well as X‐ray diffraction experiments. These two cages display ligand‐based fluorescence emissions and therefore both were chosen to be operated as fluorescent chemosensors for the detection of nitroaromatic compounds. Attractively, these metal–organic cages allow highly selective and sensitive detection of picric acid (PA) over other nitroaromatics in solution and suspension, and the fluorescence resonance energy transfer (FRET) between the cage probes and PA is mainly responsible for the remarkable detection efficiency.