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Solid-state materials with adjustable luminescence properties have always been a research hotspot due to their potential applications in optical data recording, display and ink-free printing. Further research on the multiform light-controlled luminescent switches will create a new perspective. We synthesized two isostructural compounds, namely [Me(ipbp)Cl] H2O (ipbp = 1-(3,5-dicarboxyphenyl)-4,4′-bipyridinium, Me = Cd (1), Me = Zn (2)). In the solid-state, they not only show excitation-wavelength-dependent photoluminescence emission in a wide spectral range but also exhibit good time-dependent photoluminescence emission. This study could provide a broad perspective for the development of multiform light-controlled luminescent switches. [ABSTRACT FROM AUTHOR]

We report the exploration of the stabilization effect of the in situ generated N-alkylated DABCO (DABCO = 1,4-diazabicyclo[2.2.2]octane) cation in the family of bromoplumbates and a 1-D bromoplumbate, (Et2DABCO)2n(Pb3Br10)n (1), has been prepared by solvothermal conditions. Optical diffuse reflectance determination shows the band gap of 1 is 3.69 eV, which manifests that 1 is a wide band gap semiconductor. Compared with the band gap of bulk PbBr2 (3.84 eV), 1 exhibits 0.15 eV red shift of absorption edge. While for the reported iodo analogs of this compound, (MPDA)2n(Pb3I10)n and (Et2DABCO)2n(Pb3I10)n, they exhibit 0.53 and 0.47 eV blue shift of the energy gaps compared with the measured value of 2.30 eV for bulk PbI2, respectively. The photoluminescent study of 1 shows that it exhibits a broad emission band centered at 697 nm upon photoexcitation by 345 nm (amount to 3.59 eV). The calculated density of states manifests the theoretical value of the band gap of 1 is 3.422 eV and the origination of photoluminescence can be ascribed to the transition of bonding electrons of Br– anion to the empty orbits of Pb(II) ion. [ABSTRACT FROM AUTHOR]

Four Zn(ii) tetrazolate coordination compounds have been hydrothermally synthesized and structurally determined by single-crystal X-ray diffraction. They are formulated as [Zn(3-tzbd)2]n·nH2O (1), [Zn2(3-tzbd)2(OH)2(4,4′-bipy)]n·nH2O (2), [Zn2(3-tzbd)3(N3)(4,4′-bipy)2]n·nH2O (3) and Zn2(3-tzbd)4(phen)2 (4), where 3-Htzbd = 3-(5H-tetrazol)benzaldehyde. The 3-tzbd− ligand, which was in situ generated through a [2 + 3] cycloaddition reaction of nitrile and azide, displays diverse coordination modes. Compound 1 exhibits a (4,4)-connected two-dimensional (2D) layer generated by the linkage of dinuclear units of [Zn2(μ2-3-tzbd)2] and μ2-3-tzbd− ligands. In 2, Zn(ii) atoms are connected by μ2-3-tzbd− ligands and μ3-OH− anions to form unusual double-stranded stair-like chains, which are further linked by 4,4′-bipy to create a 2D sheet. Compound 3 features an unprecedented one-dimensional (1D) four-legged, triple-ladder chain composed of tetranuclear units [Zn4(μ2-3-tzbd)4(μ2-N3)2]. Two Zn(ii) atoms in 4 are bridged by μ2-3-tzbd− ligands to result in an isolated dinuclear structure. In addition, the luminescent properties of 1–4 were investigated in the solid state at room temperature. The relevant density of states (DOS) calculation results show that their photoluminescence mainly originates from ligand-centered emission and is dependent on the organic ligand incorporated into the compounds. [ABSTRACT FROM AUTHOR]

Abstract: Five new thiogermanates, [NiII(dien)2]2(Ge2S6) (dien=diethylenetriamine) (1), [NiII(dien)2](H2pipe)(Ge2S6) (pipe=piperazine) (2), {[MnII(tren)]2(μ 2-Ge2S6)} (tren=N,N,N-tris(2-aminoethyl)amine) (3) and {[MII(tepa)]2(μ 2-Ge2S6)} (M=Mn (4a), Ni (4b); tepa=tetraethylenepentamine), have been obtained solvothermally in the presence of tri-(L3), tetra-(L4) and penta-dentate (L5) chelating amines and transition metal (TM) ions. Single-crystal X-ray diffraction analyses show that compounds 1–2 are comprised of discrete (Ge2S6)4− anions and TM complex (TMC) cations, while compounds 3–4b are composed of each dimeric (Ge2S6)4− anion bridging two TMC cations via TM–S bonds to form a neutral molecule. Notably, two interesting in situ metal/ligand reactions were observed in the solvothermal syntheses of 2 and 3. The present compounds exhibit wide optical gap ranging from 2.94 to 3.39eV and photoluminescence with the emission maxima occurring around 440 (1, 2, 3 and 4b) and 489nm (4a). Magnetic measurements show the presence of weak antiferromagnetic interactions between magnetic centers in the five compounds. [ABSTRACT FROM AUTHOR]

A photochromic inorganic–organic hybrid based on in situgenerated MV2+cation (MV2+= methyl viologen = N,N′-dimethyl-4,4′-bipyridinium) has been obtained, in which a vagarious partial photochromic phenomenon together with its photoluminescence modulation properties are reported for the first time in the inorganic–organic hybrids. [ABSTRACT FROM AUTHOR]

[Display omitted] • It is an urgent demand to achieve the multifunctional optical properties of visible photochromism and strong photoluminescence on one material. • The photochromic viologen-based MOFs rarely exhibit strong photoluminescence in both initial and colored states. • We report herein a viologen-based host-guest Eu-MOF with both visible photochromism and strong photoluminescence. • The title compound exhibits visible photochromism arising from photoinduced electron transfer from electron rich host framework to electron deficient guest viologen unit. • The title compound emits strong pink luminescence in both initial and colored states with the luminescence quantum yield of about 31.6%. A viologen-based host–guest metal–organic framework with both visible photochromism and strong photoluminescence was designed and synthesized, namely (H 2 bpyb)[Eu(btec)] 2 (bpyb = 1,4-bis(4-pyridyl)benzene, H 4 btec = 1,2,4,5-pyromellitic acid), providing an effective pathway for designing multifunctional optical materials with comprehensive performance. [ABSTRACT FROM AUTHOR]

Less attention has been paid to the solvent-dependent chirality transformation behavior of coordination compounds when using achiral precursors. We have successfully prepared one known helical achiral compound ( α -[AgL] n ∙ n H 2 O, 1 ) using water or DMSO as a solvent, one new helical homochiral MOF ( β -[AgL] n ∙ n H 2 O, 2 ) using DMF, dimethyl acetamide or ethanol as a solvent, and one new non-helical achiral compound ([Ag 2 L(NO 3 )] n , 3 ) using n -propyl alchohol or cyclohexanol as a solvent, with the V-shaped achiral ligand 3-aminobenzoic acid (HL) as a ligand. Achiral 1 can be converted from chiral isomeric 2 through recrystallization in water. Such successive chirality transformation (achirality → chirality → achirality) behavior is probably proportional the polarity of the used solvent: cyclohexanol ( 3 ) < n -propyl alchohol ( 3 ) < ethanol ( 2 ) < dimethyl acetamide ( 2 ) < DMF ( 2 ) < DMSO ( 1 ) < water ( 1 ). A preliminary study revealed that the isomeric compounds 1 and 2 displayed significantly different photoluminescence. [ABSTRACT FROM AUTHOR]

Abstract: Reaction of the 2-D MOF [AgL] n ·nH2O (1; L=4-cyanobenzoate) with pyrazine (L′) in water yielded [Ag2L2L′] n ·2nH2O (2) with a chain-like structure. Compound 1 features tunable yellow-to-white photoluminescence when its wavelength of excitation light varies. The photoluminescence of 2 obviously differs from that of 1: the former displays intense yellowish green phosphorescence with a shorter lifetime of ~3.58μs and an unresolved peak shape, and does not exhibit tunable photoluminescence upon irradiation of 280–380nm UV light. Electron transition from the [Ag2(COO)2] cluster to pyrazine is probably responsible for the phosphorescence of 2 based on the experimental and theoretical results. [Copyright &y& Elsevier]

Herein, we presented an in-situ hydrothermall y synthesized photoluminescent zinc(II) coordination polymer (Zn–CP), namely [Zn 2 (tzeba) 2 (bpy)] n 1 , in which H 2 tzeba = 3-(1-tetrazol-ethyl)benzoic acid, bpy = 4,4′-bipyridine. Compound 1 exhibits ligand-centered photoluminescence (PL) and displays interesting dual emissions based on the excitation of different chromophores from the mixed organic ligands. The PL colors of 1 could be tuned from blue-to-cyan-to-green directly by varying the excitation wavelengths. The PL mechanism has been investigated by the density of states (DOS) and density functional theory (DFT) calculations. [ABSTRACT FROM AUTHOR]

A new 1D coordination polymer [Pb(adba)(DMF)] n exhibits the competitive sensitivity, detection limit and radiation stability responsive to X-ray and could serve as a promising scintillating material candidate for X-ray detection in highly irradiating conditions. [Display omitted] • A new X-ray responsive 1D coordination polymer [Pb(adba)(DMF)] n (named as Pb-adba , H 2 adba = 4,4′-(9,10-anthracenediyl)dibenzoic acid, DMF = N , N -dimethylformamide) was constructed with Pb(II) salt and H 2 adba by a mild solvothermal process. • Pb-adba exhibits the competitive sensitivity and detection limit toward X-ray than classical scintillators PbWO 4 (PWO), anthracene and some reported SMOFs. • Pb-adba possess favorable radiation stability at the dose rate of 42.29 mGy/s for 3 h (equivalent to the cumulative dose of 456 Gy). The strong X-ray attenuation and beneficial optoelectronic properties of lead(II)-based coordination polymers (CPs) materials have aroused great interest in the field of radiation detection. In this work, a X-ray responsive scintillating 1D Pb(II)-CP [Pb(adba)(DMF)] n (named as Pb-adba , H 2 adba = 4,4′-(9,10-anthracenediyl)dibenzoic acid, DMF = N , N -dimethylformamide) with favourable irradiation stability was synthesized by the self-assembly approach, which exhibits competitive sensitivity and detection limit toward X-ray than classical scintillators PbWO 4 (PWO), anthracene and some reported SMOFs. [ABSTRACT FROM AUTHOR]

Abstract: We report a new non-interpenetrated 2D zinc coordination polymer, [Zn(AA)(BPHY)] n (1) (H2AA=adipic acid, BPHY=1,2-bis(4-pyridyl)hydrazine), which is a mixed ligand complex. The solid-state sample of 1 exhibits tunable blue emission excited by UV light with the wavelengths from 320nm to 380nm. The luminescent mechanism of 1 has been studied by theoretical calculation. [Copyright &y& Elsevier]

Abstract: Two polycatenated coordination polymers, {[Zn3(adc)3(bpp)4]2 ·3H2O} n (1) and [Zn(adc)(bphy)] n (2) (adc=azobenzene-4,4′- dicarboxylate, bpp=1,3-bis(4-pyridyl)propane, bphy=1,2-bis(4-pyridyl)hydrazine), have been obtained from Zn(NO3)2∙6H2O, linear H2adc ligand and arched bpp/azpy (azpy=4,4′-azobispyridine) ligands by hydro(solvo)thermal reactions. Compound 1 presents a 2-D structure catenated from 1-D double ladders (1-D→2-D polycatenation), while compound 2 displays a 3-D structure catenated from 2-D (4,4) stair-stepping layers (2-D→3-D polycatenation). Luminescence properties of 1 and 2 have been explored, together with study of photoluminescent mechanism by density of states (DOS) calculation. [Copyright &y& Elsevier]

A novel open-framework cadmium selenite bromide, [Cd10(SeO3)8Br4]·HBr·H2O (1), has been obtained by a solid-state reaction at 450°C, and the structure has been determined by single-crystal X-ray diffraction analysis. Compound 1 crystallizes in Pbcm of the orthorhombic system: a=10.882(3), b=16.275(5), c=18.728(6)Å, V=3317(2)Å3, R1/wR2=0.0411/0.0659. Compound 1 is characteristic of a novel 3-D open-framework structure, composing ∞ 2[CdSeO3] layers and the pillars of edge-shared CdO3Br2 square pyramids. The lattice water molecules and the HBr molecules locate in the voids of the framework. Optical absorption spectrum of 1 reveals the presence of an optical gap of 1.65eV. Solid-state photoluminescent study indicates that compound 1 exhibits strong violet emission. TG–DSC measurement shows that compound 1 is thermally stable up to 200°C. [ABSTRACT FROM AUTHOR]

Abstract: Hydrothermal reaction of methyl 4-(cyanomethoxy)benzoate, Cd(NO3)2·4H2O and NaN3 yielded a new 2D Cd(II) coordination polymer, {[Cd3(N3)2(mtzb)4(H2O)2]·(H2O)2.5}n 1 (Hmtzb=methyl 4-(1H-tetrazol-5-ylmethoxy)benzoate), which was characterized by single-crystal X-ray diffraction. The in situ [2+3] cycloaddition reaction of nitrile and azide in presence of Cd(II) salt afforded a new tetrazolate-based mtzbˉ ligand. In polymer 1, The cross-linkage of the mtzbˉ ligands and Cd(II) atoms forms a 2D layer network, and the mtzbˉ ligand displays two distinct μ3-bridging coordination modes, μ 3-κN1:κN2:κN3 and μ 3-κN1:κN2:κN4. Photoluminescent analyses revealed that 1 exhibits a strong blue emission with a fluorescent lifetime of 3.22ns. The relevant density of states (DOS) calculation results showed that the photoluminescence mainly originates from ligand-centered charge transition. [Copyright &y& Elsevier]

Abstract: Inorganic–organic hybrids with mixed halo atoms or organically coordinated halometal-complex cations are rare. A series` of haloplumbate hybrids with these structural features, [Cu(phen)2Cl] n (PbCl3) n (phen = 1,10-phenanthroline) (1), [Cu(phen)2Cl] n [PbClI(Cl0.5I0.5)] n (2), and [Cu(phen)2I] n (PbI3) n (3), have been solvothermally synthesized using phen coordinated halocopper(II) complexes as templates and balance cations. Their haloplumbate ions all show 1-D chain structures. Compounds 1–3 feature the hybridization of inorganic–organic hybrids: 1) their absorption edges fall in the range of those of semiconductors, which is typical for bulk lead(II) halides, but show a red shift compared with those of the latter; 2) bulk lead(II) halides are nonluminous upon UV irradiation, but introduction of the phen coordinated halocopper(II) complexes as templates enable the hybrids to emit blue light. Their luminescent intensities gradually decrease with the increase of I content, which indicates the potential to design and syntheses of new luminescent halide materials by means of variation of halo atoms and that iodoplumbates are not good candidates for luminescent materials. [Copyright &y& Elsevier]

Abstract: Two inorganic–organic hybrids, (MPDA)2n (Pb3I10) n (MPDA= p-Me3NC6H4NMe3) (1) and (H2EPDA) n (Pb2I6) n ·2nH2O (H2EPDA= p-Et2NHC6H4NHEt2) (2), have been solvothermally synthesized using p-phenylenediamine (PDA) as a precursor. Their iodoplumbate ions all show 1-D chain structures, but differ in interlinkage modes of [PbI6] octahedra: the former is both face- and edge-sharing, while the latter is face-sharing. The chain-like structure in 1 was reported only once in the literature. The results of optical absorption spectra and theoretical calculations for compounds PbI2 and 1–2 reveal a quantum confinement effect. Photoluminescent analyses show that they all exhibit blue emissions upon UV irradiation, which mainly originate from charge transfer from iodine atoms to ammoniums. [Copyright &y& Elsevier]

Abstract: Hydrothermal reaction of diethyl 2-(2-cyanoethyl) malonate, ZnCl2, NaN3 and NaOH yielded a new 1H-tetrazolate-5-butyrate coordination polymer, [Zn(tzb)]n (1) (H2tzb=1H-tetrazolate-5-butyric acid), which presents a 3-D noninterpenetrating diamond network. The in situ generated tzb2− ligand adopts a μ4-bridging mode with carboxylate group in a syn–anti fashion and tetrazolate group in a 1,4-N manner. Polymer 1 exhibits a weak second-order nonlinear optical coefficient about 0.5 times that of potassium dihydrogen phosphate (KDP), and also displays strong blue photoluminescence at room temperature and a high thermal stability up to 400°C. [ABSTRACT FROM AUTHOR]

Abstract: A new approach has been used to synthesize MQ+ ligand (MQ+ =N-methyl-4,4′-bipyridinium) by the reaction of 4,4′-bipyridine and chloroacetic acid, and the structure of (MQ)Cl·H2O ( 1 ) was first determined. Three new complexes containing MQ+, (MQ)CdI3 ( 2 ), (MQ)ZnI3 ( 3 ), and [(MQ)ZnCl1.53I1.47]2(MQ)ZnCl1.68I1.32 ( 4 ), were successfully obtained via a solution or hydrothermal method by reaction of MI2 (M=Cd, Zn) with 1 , and each of which exhibits an isolated structure, with each metal atom coordinated by one MQ+ ligand and three terminal halogen atoms. Compounds 1 2 3 – 4 all display photoluminescence in the visible region under visible-light excitation, and the origins of the emissions have been assigned to ILCT for 1 and the combination of ILCT and LLCT for 2 3 – 4 . [Copyright &y& Elsevier]

Abstract: Compared to previously reported methods, a less hazardous approach has been used to synthesize N-methylpyrazinium cation (mpz+) by the reaction of pyrazine and ClCH2COONa. Although a few mpz+-containing complexes have been documented, there is no example of mpz+-containing group IIB metal complexes. Three novel complexes containing mpz+, (mpz)ZnI3 (1), [(mpz)CdCl3] n (2), and [(mpz)CdBr3] n (3), have been successfully obtained via a solution or hydrothermal method by reactions of ZnI2, CdCl2·2.5H2O, and CdBr2·4H2O with the mpz+ ligand, respectively. Complex 1 features an isolated structure, with each zinc atom coordinated by one mpz+ ligand and three terminal iodine atoms. The CD spectra of 1 reveal that it exhibits spontaneous resolution. Complexes 2 and 3 are isotypic, and exhibit chain structures made by linear arrays of Cd(II) bridged by halogen atoms. Photoluminescent analyses reveal that complexes 1–3 exhibit strong blue emissions originating from intra-ligand π–π∗ transition of the mpz+ ligand. [Copyright &y& Elsevier]

A 3-D metal-organic framework [Cd(BPHY)(SA)] n 1 (BPHY = 1,2-bis(4-pyridyl)hydrazine, H 2 SA = succinic acid) has been solvothermally synthesized. Compound 1 features a 2-fold pillar-layered structure and crystallizes in a non-centrosymmetric space group ( I 2). It is testified to be second harmonic generation (SHG) active. The blue photoluminescence of 1 is attributed to BPHY-centered charge transition demonstrated by theoretical calculation. [ABSTRACT FROM AUTHOR]