Zhi-Gang Ren

pH-dependent solvothermal formation of two different 3D multiple interpenetrating nets from the same components of Zn(NO3)2, 1,3-benzenedicarboxylate and 1,4-bis[2-(4-pyridyl)ethenyl]benzene

Hydrothermal reactions of Zn(NO3)2·6H2O with 1,3-benzenedicarboxylic acid (1,3-H2BDC) and 1,4-bis[2-(4-pyridyl)ethenyl]benzene (1,4-bpeb) under pH = 2.5 or 8.0 gave rise to two coordination polymers {[Zn6(μ-OH2)(1,3-BDC)6(1,4-bpeb)4]·MeCN}n (1) and {[Zn8(1,3-BDC)8(1,4-bpeb)4]·2H2O}n (2). Both compounds were characterized by elemental analysis, IR, powder X-ray diffraction, and single-crystal X-ray diffraction. Compound 1 has two types of dinuclear zinc cores as nodes and displays an intriguing three-dimensional (3D) three-fold interpenetrating (4,6)-connected network with an unprecedented (3264)(3244687)2 topology. Compound 2 exhibits an unusual 3D two-fold interpenetrating pcu net with a Schlafli symbol 41263. The formation of 1 and 2 provided an interesting insight into the effect of pH values on the construction of coordination polymers under solvothermal conditions. Thermal stability and photoluminescence properties of 1 and 2 were also investigated.

Using alcohols as alkylation reagents for 4-cyanopyridinium and N,N′-dialkyl-4,4′-bipyridinium and their one-dimensional iodoplumbates

Solvothermal reactions of PbI2 with 4-cyanopyridine (4-cypy) or 4,4′-bipyridine (4,4′-bipy) and alcohols (ethanol, propanol, iso-propanol, benzyl alcohol, α,α′-dihydroxy-p-xylene) in the presence of PbI2, I2 and a trace amount of water in acetonitrile gave rise to a family of 1D iodoplumbate complexes of 4-cyanopyridinium and N,N′-dialkyl-4,4′-bipyridinium including {[EC]4[(Pb2I6)2]·2MeCN}n (EC+ = N-ethyl-4-cyanopyridium) (1), {[PC][PbI3]}n (PC+ = N-propyl-4-cyanopyridium) (2), {[iPC]3[(PbI3)(Pb2I6)]}n (iPC+ = N-isopropyl-4-cyanopyridium) (3), {[BzC][PbI3]}n (BzC+ = N-benzyl-4-cyanopyridium) (4), {[Cxy]2[(Pb2I6)2]}n (Cxy2+ = 1,4-bis(4-cyanopyridium)-xylene) (5), {[EV]1.5[Pb3I9]}n (EV2+ = N,N′-diethyl-4,4′-bipyridinium) (6), {[PV]1.5[Pb3I9]}n (PV2+ = N,N′-dipropyl-4,4′-bipyridinium) (7), and {[iPV]2[Pb4I12]}n (iPV2+ = N,N′-diisopropyl-4,4′-bipyridinium) (8). The resulting 4-cyanopyridinium and viologen cations were generated in situ via the cleavage of C–O bond of alcohols followed by alkylation of 4-cypy or 4,4′-bipy. X-Ray analysis revealed that compounds 1–8 contain one-dimensional anionic [PbI3]nn− (1–5, 8) and [Pb3I9]n3n− (6 and 7) chains that are enclosed into the different cationic channels formed from the 4-cyanopyridinium and N,N′-dialkyl-4,4′-bipyridinium. In addition, the optoelectronic and dielectric properties of 1–8 were also investigated.

Construction of Cd(II) coordination polymers used as catalysts for the photodegradation of organic dyes in polluted water

Four Cd(II) coordination polymers formulated as {[Cd3(tpcb)2)(η,η-μ-SO4)2(H2O)6]SO4·16H2O}n (1), {[Cd(tpcb)0.75(OH)(H2O)2](NO3)}n (2), {[Cd2(tpcb)(SO4)2(H2O)6]·2MeOH·3H2O}n (3), and {[Cd(tpcb)(NO3)(H2O)2](NO3)}n (4) were synthesized by reactions of CdSO4 or Cd(NO3)2 with tetrakis(4-pyridyl)cyclobutane (tpcb) under solvothermal conditions or at ambient temperature. Compounds 1–4 were characterized by elemental analysis, IR spectroscopy, thermal analysis, powder X-ray diffraction analysis and single crystal X-ray diffraction. Compounds 1, 2, and 4 possess three different complicated 3D frameworks with the Schlafli symbols of (46)(412·54·64·88), (63)4(62·84)3 and (83)(86), respectively, while 3 presents a 1D chain structure. Compounds 1–4 exhibited relatively good photocatalytic activity towards the degradation of methyl orange (MO), methyl blue (MB) and rhodamine B (RhB) in aqueous solution. These results offered a good insight into the temperature effects on the assembly of Cd(II) coordination polymers and their photocatalytic applications.

Cracking the framework of bulk CuCN with flexible bipyrazolyl-based ligands to assemble [CuCN]n-based coordination polymers

Solvothermal reactions of CuCN with a set of flexible bipyrazolyl-based ligands with different spacer lengths [(dmpz)(CH(2))(n)(dmpz)] (dmpz = 3,5-dimethyl-pyrazolyl; n = 1-6) gave rise to six [CuCN](n)-based coordination polymers [(CuCN)(3)L](n) (1: L = dmpzm; 2: L = dmpze), [(CuCN)(2)L](n) (3: L = dmpzpr; 4: L = dmpzb; 5: L = dmpzp; 6: L = dmpzh). Compounds 1-6were characterized by elemental analysis, IR, powder X-ray diffraction and single-crystal X-ray diffraction. 1 or 2 exhibits a 1D scolopendra-like chain assembled from a rare 1D zigzag [CuCN](n) chain with [CN-Cu-CN-Cu-L] (1: L = dmpzm; 2: L = dmpze) side arms. 3 or 4 shows a 2D (6,3) wave-like layer in which [Cu(6)(mu-CN)(6)L(2)](n) (L = dmpzpr or dmpzb) double chains are interconnected by pairs of L bridges. 5 consists of two [CuCN](n) single chains that are linked by dmpzp bridges to form a rare 1D chain with an oblong channel. has a 3D network in which the 2D [Cu(10)(mu-CN)(10)(dmpzh)(3)](n) layers are interconnected by pairs of dmpzh bridges. In addition, the photoluminescent properties of 1-6 in the solid state at ambient temperature were investigated.

How do substituent groups in the 5-position of 1,3-benzenedicarboxylate affect the construction of supramolecular frameworks?

Four 1,3-benzenedicarboxylic acid derivatives, with substituted R (OH, COOH, NO2, Me) groups at the 5-position, were employed to explore their effect on the construction of supramolecular assemblies. Four coordination polymers, [Zn(OH2)(5-HO-1,3-BDC)(1,4-bpeb)]n (1), [Zn(1,3,5-HBTC)(1,4-bpeb)]n (2), {[Zn(5-NO2-1,3-BDC)(1,4-bpeb)]·2(H2O)0.5}n (3), and [Zn(5-Me-1,3-BDC)(1,4-bpeb)]n (4) (1,4-bpeb = 1,4-bis[2-(4-pyridyl)ethenyl]benzene, 5-HO-1,3-BDC = 5-hydroxy-1,3-benzenedicarboxylate, 1,3,5-H3BTC = 1,3,5-benzenetricarboxylate, 5-NO2-1,3-BDC = 5-nitro-1,3-benzenedicarboxylate, 5-Me-1,3-BDC = 5-methyl-1,3-benzenedicarboxylate) were prepared by the hydrothermal reactions of Zn(NO3)2·6H2O with 1,4-bpeb and 5-HO-1,3-H2BDC, 1,3,5-H3BTC, 5-NO2-1,3-H2BDC or 5-Me-1,3-H2BDC. All these compounds were characterized by elemental analysis, IR, powder X-ray diffraction, and single-crystal X-ray diffraction. The structure of 1 has a 3D H-bonded structure derived from linking 1D comb-like [Zn(OH2)(5-HO-1,3-BDC)(1,4-bpeb)]n chains via intermolecular H-bonding interactions between the coordinated H2O molecule and 1,4-bpeb or one COO− group and between the OH group and the other COO− group. 2 has a 3D H-bonded net based on holding 2D [{Zn2(1,3,5-HBTC)2}4]n layers through intermolecular H-bonding interactions between 1,4-bpeb and the uncoordinated COOH group. 3 could be considered as a 6-fold interpenetrating 3D H-bonded supramolecular framework constructed by linking 2D [Zn4(5-NO2-1,3-BDC)4(1,4-bpeb)4]n networks through intermolecular H-bonding interactions between the water solvent molecules and the NO2 group. 4 has a 3-fold interpenetrating 3D framework in which each 2D (4,4) [Zn4(5-Me-1,3-BDC)4(1,4-bpeb)4]n network is interpenetrated by two other equivalent nets. The Schlafli symbols for the four supramolecular frameworks are 41263, (4·62)2(426687), (63)(658) and 4462, respectively. The thermal stability and photoluminescent properties of 1–4 were also investigated.

Multi-dimensional iodocuprates of 4-cyanopyridinium and N,N′-dialkyl-4,4′-bipyridinium: syntheses, structures and dielectric properties

Solvothermal reactions of CuI with 4-cyanopyridine (4-cypy) or 4,4′-bipyridine (4,4′-bipy) and alcohols (methanol, ethanol, propanol, isopropanol) in the presence of I2 and a trace amount of water in acetonitrile gave rise to a family of multi-dimensional iodocuprate complexes of 4-cyanopyridinium and N,N′-dialkyl-4,4′-bipyridinium including {[MC]2[Cu4(μ3-I)4(μ-I)2]}n (MC+ = N-methyl-4-cyanopyridium) (1), {[PC][(Cu2I4)1/4(Cu2I4)1/4]}n (PC+ = N-propyl-4-cyanopyridinium) (2), {[iPC][(Cu2I4)1/4((Cu1/2)4I4)1/4]}n (iPC+ = N-isopropyl-4-cyanopyridium) (3), {[EV]1/4[((Cu1/2)4I4)1/4]}n (EV2+ = N,N′-diethyl-4,4′-bipyridinium) (4) and {[PV]1/2[(Cu2I4)1/4((Cu1/2)4I4)1/4]}n (PV2+ = N,N′-dipropyl-4,4′-bipyridinium) (5). The resulting 4-cyanopyridinium and viologen cations were generated in situ via the cleavage of the C–O bond of alcohols followed by alkylation of 4-cypy or 4,4′-bipy. X-ray analysis revealed that compound 1 consists of a unique three-dimensional anionic [Cu4I6]n2n− framework while compounds 2–5 contain one-dimensional anionic [Cu2I4]n2n− chains that are enclosed into different cationic channels formed by either 4-cyanopyridinium or N,N′-dialkyl-4,4′-bipyridinium. The dielectric properties of 1–5 were investigated.

Luminescent Zn(II) Coordination Polymers for Highly Selective Sensing of Cr(III) and Cr(VI) in Water

Three photoluminescent zinc coordination polymers (CPs), {[Zn2(tpeb)2(2,5-tdc)(2,5-Htdc)2]·2H2O}n (1), {[Zn2(tpeb)2(1,4-ndc)(1,4-Hndc)2]·2.6H2O}n (2), and {[Zn2(tpeb)2(2,3-ndc)2]·H2O}n (3) (tpeb = 1,3,5-tri-4-pyridyl-1,2-ethenylbenzene, 2,5-tdc = 2,5-thiophenedicarboxylic acid, 1,4-ndc = 1,4-naphthalenedicarboxylic acid, and 2,3-ndc = 2,3-naphthalenedicarboxylic acid) were prepared from reactions of Zn(NO3)2·6H2O with tpeb and 2,5-H2tdc, 1,4-H2ndc, or 2,3-H2ndc under solvothermal conditions. Compound 1 has a two-dimensional (2D) grid-like network formed from bridging 1D [Zn(tpeb)]n chains via 2,5-tdc dianions. 2 and 3 possess similar one-dimensional (1D) double-chain structures derived from bridging the [Zn(tpeb)]n chains via pairs of 1,4-ndc or 2,3-ndc ligands. The solid-state, visible emission by 1-3 was quenched by Cr3+, CrO42-, and Cr2O72- ions in water with detection limits by the most responsive complex 3 of 0.88 ppb for Cr3+ and 2.623 ppb for Cr2O72- (pH = 3) or 1.734 ppb for CrO42- (pH = 12). These values are well below the permissible limits set by the USEPA and European Union and the lowest so far reported for any bi/trifunctional CPs sensors. The mechanism of Cr3+ luminescence quenching involves irreversible coordination to free pyridyl sites in the CP framework, while the Cr6+ quenching involves reversible overlap of the absorption bands of the analytes with those of the excitation and/or emission bands for 3.

A Mn(iii)–superoxo complex of a zwitterionic calix[4]arene with an unprecedented linear end-on Mn(iii)–O2 arrangement and good catalytic performance for alkene epoxidation

Reactions of [H(4)L][PF(6)](4) with 4 equiv. of Mn(OAc)(2)·4H(2)O in the presence of air gave rise to a mononuclear Mn(III)-superoxo complex [Mn(III)L(O(2))(H(2)O)](PF(6))(2), which contains a bowl-shaped cationic structure with a D(4d) symmetry. It has an unprecedented linear end-on Mn(III)-O(2) unit and exhibited good efficiency and selectivity in the catalytic oxidation of alkenes with O(2) plus isobutyraldehyde under mild conditions.

Cleaving the framework of CuX with a tetrapyrazolyl-based ligand to construct [CuX]n-based coordination polymers

Reactions of CuX (X = Cl, Br, I, SCN, CN) with 1,1,3,3-tetrakis(3,5-dimethyl-1-pyrazole)propane (tdmpp) gave rise to five coordination polymers, [{Cu2X2(tdmpp)}·Sol]n (1: X = Cl, Sol = 0.5MeCN; 2: X = Br, Sol = 0.5MeCN; 3: X = I, Sol = MeCN; 4: X = SCN), and [Cu3(CN)3(tdmpp)]n (5). Compounds 1–5 were characterized by elemental analysis, IR, and single crystal X-ray diffraction. Compounds 1–4 contain a 1D helical (1–3) or linear (4) chain assembled by [CuX]2 cores and tdmpp ligands. While for 5, the zigzag [CuCN]n chain is linked by tdmpp ligands to form a 2D (4,4) staircase network. The oxidation state of copper in these coordination networks is assumed to be +1. The solid state luminescent properties of compounds 1–5 at ambient temperature were also investigated.

Spacer length-controlled assembly of [CunIn]-based coordination polymers from CuI and bis(4-phenylpyrimidine-2-thio)alkane ligands

Reactions of CuI with bis(4-phenylpyrimidine-2-thio)alkane ligands with different spacer lengths, [(phpy)(CH2)n(phpy)] (phpyH = 4-phenylpyrimidine-2-thiol; n = 1, bphpym; n = 2, bphpye; n = 3, bphpypr; n = 4, bphpyb; n = 5, bphpyp; n = 6, bphpyh), afforded a set of six [CunIn]-based coordination polymers, [{Cu(μ3-I)}2(phpym)]n (1), [{Cu(μ3-I)}4(bphpye)]n (2), [{(MeCN)Cu3(μ-I)2(μ4-I)}2(bphpypr)2]n (3), [{((MeCN)Cu)(μ-I)}2(bphpyb)]n (4), [{Cu2(μ-I)(μ3-I)}2(bphpyp)2]n (5) and [{((MeCN)Cu)(μ3-I)}2{Cu(μ-I)}2(bphpyh)2]n (6), respectively. Compounds 1–6 were characterized by elemental analysis, IR and single-crystal X-ray crystallography. 1 and 2 consist of an unique 2D network in which the 1D staircase [Cu2I2]n chains are linked by phpym or phpye ligands via the μ-η1(N)-η1(N) or μ-η1(N),η1(S)-η1(N),η1(S) coordination modes, respectively. Complexes 3 and 5 consist of double butterfly-shaped {(MeCN)Cu3(μ-I)2(μ4-I)}2 units or chair-like [Cu2(μ-I)(μ3-I)]2 units that are linked to their neighboring ones by pairs of bphpypr or bphpyp bridges to form a 1D double chain. 4 contains a 1D zigzag chain assembled by dimeric [{(MeCN)Cu}(μ-I)]2 cores and bphpyb ligands. In 6, unique 1D tandem-rhomboid [Cu2I2]n chains are connected by dphpyh ligands to form a 2D staircase network. In addition, the photoluminescent properties of 1–6 in the solid state at ambient temperature were investigated.