Hydrothermal synthesis, crystal structures and photoluminescent properties of four cadmium(II) coordination polymers derived from diphenic acid and auxiliary ligands

Four novel metal coordination polymers, [Cd(dpa)(H₂O)]_n (1), [Cd(dpa)(2,2′-bipy)]_n (2), {[Cd₂(dpa)₂(4,4′-bipy)₃](4,4′-bipy)(H₂O)₂}_n (3) and [Cd(dpa)(bim)₂(H₂O)]}_n (4) (H₂dpa = 2,4′-biphenyl-dicarboxylic acid, 2,2′-bipy = 2,2′-bipyridine, 4,4′-bipy = 4,4′-bipyridine, bim = benzimidazole), have been synthesized and structurally characterized by elemental analysis, IR and X-ray diffraction. Single-crystal X-ray analyses reveal that the 2,4′-diphenic acids acts as bridging ligands, exhibiting rich coordination modes to link metal ions: bis-monodentate, bidentate chelating, chelating/bridging, monoatomic bridging and monodentate modes. In addition, the luminescent properties for compound 1-4 are also investigated in this work.     

The effect of organic acid on self-assembly process: Syntheses and characterizations of six novel cadmium(II)/zinc(II) complexes derived from mixed ligands

Using the principle of crystal engineering, six metal-organic coordination polymers, [Cd(bdc)(3-pytpy)]_n · 2nH₂O (1), [Cd(bdc)_0.5(3-pytpy)]_n · n(ClO₄) (2), Cd(ndc)_0.5(3-pytpy)]_n · n(ClO₄) (3), [Zn(ndc)(3-pytpy)]_n (4), [Cd(bqdc)(3-pytpy)]_n (5), and [Zn(pam)(3-pytpy)]_n · 2nH₂O (6) (H₂bdc = benzene-1,4-dicarboxylic acid, H₂ndc = naphthalene-2,6-dicarboxylic acid, H₂bqdc = 2,2′-biquinoline-4,4′-dicarboxylic acid, H₂pam = pamoic acid), were synthesized and structurally characterized by elemental analyses, IR spectroscopy, and single-crystal X-ray diffraction analyses. Compounds 1-6 crystallize in the presence of organic-acid linkers as well as multi-functional N-donor ligand 4′-(3-pyridyl)-2,2′:6′,2′′-terpyridine (3-pytpy). In complexes 1, 4, 5, and 6, the dicarboxylate as bridging ligand connects metal atoms to form the main body of 1D zigzag chains for 1 and 4, nearly linear chain for 5 and helical chain for 6, while 3-pytpy as tridentate chelating ligand is just like lateral arm grafting on both sides of these chains. In complexes 2 and 3, both the dicarboxylate and 3-pytpy as bridging ligands connect metal atoms into 2D polymeric structure for 2 and 1D chain of alternating loops and rods for 3. The weak interactions such as hydrogen bonding and π···π stacking were investigated on the formation of superamolecular structures and the influence of organic acid on the formation of the final structures was discussed. In addition, the photoluminescent properties of 1-6 were also determined.     

New photoluminescence coordination polymers constructed from different ligands, which are generated from maleic acid at hydrothermal conditions

A new coordination polymer, [Zn₂(mal)(1,10-phen)Cl]_n (1), (mal = malate, 1,10-phenanthroline), has been synthesized with malic acid and fumaric acid which are generated from maleic acid under hydrothermal reactions. At about the same condition, we get [Cd(fma)(2,2′-bpy)(H₂O)]_n (2) (fma = fumarate, 2,2′-bpy=2, 2′-bipyridine). The diverse products illustrate that the carbon-carbon doublebond of the maleic acid has two kinds of reaction trends under different conditions. Complex 1, which displays a two-dimensional (4, 8) lattice-type network, is formed from Zn and maleic through the addition reaction with water molecule. If the Zn is changed by Cd, at the same reaction condition with 1, a two-dimensional supramolecular network complex 2 is formed through the conformation transform reaction. To our knowledge, a lot of coordination polymers have been constructed from malic acid and fumaric acid directly; however, these kinds of complexes have seldom been synthesized from maleic acid under hydrothermal reaction. As is known, the rigid carbon-carbon double bond makes maleic acid lead to some unique structural features which the saturated aliphatic acid does not possess. To illustrate this clearly, a simple one dimensional complex 3, [Cd(glut)(1,10-phen)(H₂O)]_n (glut = glutarate), is synthesized. Furthermore, complex 1 and complex 3 exhibit intense photoluminescent property at room temperature.     

A comparative study of ferrocenyl carboxylate cadmium(II) complexes prepared by two different synthetic methods

Reaction of ferrocenyl carboxylate H₂bfcs with Cd(Ac)₂ · 2H₂O (H₂bfcs = 1,1′-bis(3-carboxy-1-oxopropyl)ferrocene) gives the mononuclear tetrahydrate precursor Cd(Hbfcs)₂(H₂O)₄ (1). Investigation on the substitution reactions of 1 with imidazole or 2,2′-bpy afforded two one-dimensional (1D) complexes {[Cd₂(bfcs)₂(C₃H₄N₂)₆] · 4H₂O}_n (2) and {[Cd(bfcs)(2,2′-bpy)(H₂O)] · 2H₂O}_n (4) (2,2′-bpy = 2,2′-bipyridine), respectively. However, the one-step reactions of H₂bfcs, Cd(Ac)₂ · 2H₂O with imidazole or 2,2′-bpy result in the formation of two different 1D complexes {[Cd(bfcs)(C₃H₄N₂)₂] · CH₃OH · 2H₂O}_n (3) and [Cd(bfcs)(CH₃OH)]_n (5). It can be seen from the results that applying different synthetic routes produce dissimilar complexes from however the same materials and under the same reaction conditions. In addition, investigations of differential pulse voltammetry of these four 1D complexes indicate that their half-wave potentials are slightly higher than that of H₂bfcs.     

A series of metal-organic frameworks constructed with 2,2′-bipyridine-3,3′-dicarboxylate: Syntheses, structures, and physical properties

To determine the influence of metal ion and the auxiliary ligand on the formation of metal-organic frameworks, six new coordination polymers, {[Mn₂(bpdc)(bpy)₃(H₂O)₂] · 2ClO₄ · H₂O}_n (1), {[Mn(bpdc)(dpe)] · CH₃OH · 2H₂O}_n (2), {[Cu(bpdc)(H₂O)₂]}_n (3), {[Zn(bpdc)(H₂O)₂]}_n (4), {[Cd(bpdc)(H₂O)₃] · 2H₂O}_n (5), and {[Co(bpdc)(H₂O)₃] · 0.5dpe · H₂O}_n (6) (H₂bpdc = 2,2′-bipyridine-3,3′-dicarboxylic acid, bpy = 2,2′-bipyridine, dpe = 1,2-di(4-pyridyl) ethylene), have been synthesized and characterized. Compound 1 forms 1D helical chain structure containing two unique Mn^II ions. In 2, the bridging ligand dpe links Mn-bpdc double zigzag chains to generate a layer possesses rectangular cavities. In 3, bpdc²⁻ ligand connects to three metal centers forming a 2D network. Different from the above compounds, 4 displays a 1D double-wavelike chain. Compound 5 features a helical chain. Compound 6 also displays a helical chain with guest molecule dpe existing in the structure. These diverse structures illustrate rational adjustment of metal ions and the second ligand is a good method for the further design of helical compounds with novel structures and properties. In addition, the magnetic properties of 2, 3 and 6, the thermal stabilities and photoluminescence properties of 4 and 5 were also studied.     

Four metal-organic networks based on benzene-1,4-dioxyacetic acid and dipyrido[3,2-a:2′,3′-c]phenazine ligand

Four structurally diverse complexes, [Cd(dppz)(bdoa)]_n (1), [Zn(dppz)(bdoa)(H₂O)]_n (2), [Fe(dppz)₂(bdoa)]_n·2nH₂O (3), and [Co₂(dppz)₂(bdoa)₂(H₂O)]_n·3nH₂O (4), where H₂bdoa = benzene-1,4-dioxyacetic acid and dppz = dipyrido[3,2-a:2′,3′-c]phenazine, have been hydrothermally synthesized. Compounds 1-4 feature chain structures. There exist π-π interactions in the structures of 1, 2 and 4. Two neighboring chains of 1 are linked through the π-π interactions into a double chain supramolecular structure. The chains of 2 and 4 are further extended by the π-π interactions to form 3D and 2D supramolecular structures, respectively. The structural differences among such complexes show that the transition metals have important influences on their structures. The photoluminescent property of complex 2 and the magnetic property of complex 4 have also been investigated.     

Self-assembly of two fluorescent supramolecular frameworks constructed from unsymmetrical benzene tricarboxylate and bipyridine

Two new supramolecular compounds, [Ag(4,4′-bipy)]_n [Ag(HBTC)]_n (1) and [Cu(H₂BTC)(2,2′-bipy)] (2) (HBTC/H₂BTC = 1,2,4-benzenetricarboxylate, 4,4′-bipy/2,2′-bipy = 4,4′/2,2′-bipyridine), have been synthesized and characterized by elemental analyses, IR spectra, ultraviolet-visible diffuse reflection integral spectra (UV-Vis DRIS), fluorescent spectra, thermogravimetric analysis and single crystal X-ray diffraction analysis. It is noteworthy that there were two kinds of one-dimensional stairs-chain including cationic [Ag(4,4′-bipy)]_n chain and anionic [Ag(HBTC)]_n chain in 1. Furthermore, a two-dimensional double layer supramolecular framework was constructed through coordination bonds, hydrogen bonds, π-π stacking interactions and Ag?O weak coordinative interactions. The one-dimensional supramolecular chain of 2 was built from combining mononuclear [Cu(H₂BTC)(2,2′-bipy)] by inter- and intra-molecular hydrogen bonding interactions. Additionally, the two complexes exhibit intense blue or olivine luminescence at room temperature.     

Interaction of Pt(II) and Pd(II) complexes of terpyridine with 1-methylazoles: A combined experimental and density functional study

The synthesis and characterization of several complexes of the composition [{M(terpy)}_n(L)](ClO₄)_m (M = Pt, Pd; L = 1-methylimidazole, 1-methyltetrazole, 1-methyltetrazolate; terpy = 2,2′:6′,2″-terpyridine; n = 1, 2; m = 1, 2, 3) is reported and their applicability in terms of a metal-mediated base pair investigated. Reaction of [M(terpy)(H₂O)]²⁺ with 1-methylimidazole leads to [M(terpy)(1-methylimidazole)](ClO₄)₂ (1: M = Pt; 2: M = Pd). The analogous reaction of [Pt(terpy)(H₂O)]²⁺ with 1-methyltetrazole leads to the organometallic compound [Pt(terpy)(1-methyltetrazolate)]ClO₄ (3) in which the aromatic tetrazole proton has been substituted by the platinum moiety. For both platinum(II) and palladium(II), doubly metalated complexes [{M(terpy)}₂(1-methyltetrazolate)](ClO₄)₃ (4: M = Pt; 5: M = Pd) can also be obtained depending on the reaction conditions. In the latter two compounds, the [M(terpy)]²⁺ moieties are coordinated via C5 and N4. X-ray crystal structures of 1, 2, and 3 are reported. In addition, DFT calculations have been carried out to determine the energy difference between fully planar [Pd(mterpy)(L)]²⁺ complexes Ip-IVp (mterpy = 4′-methyl-2,2′:6′,2″-terpyridine; L = 1-methylimidazole-N3 (I), 1-methyl-1,2,4-triazole-N4 (II), 1-methyltetrazole-N3 (III), or 3-methylpyridine-N1 (IV)) and the respective geometry-optimized structures Io-IVo. Whereas this energy difference is larger than 70 kJ mol⁻¹ for compounds I, II, and IV, it amounts to only 0.8 kJ mol⁻¹ for the tetrazole-containing complex III, which is stabilized by two intramolecular C-H?N hydrogen bonds. Of all complexes under investigation, only the terpyridine-metal ion-tetrazole system with N3-coordinated tetrazole appears to be suited for an application in terms of a metal-mediated base pair in a metal-modified oligonucleotide.     

Communication of metal ions in the dinuclear ruthenium complexes containing 4,4′-bipyridine, 1,4-diisocyanobenzene, and pyrazine bridging ligands: Synthesis, characterization and structure determination

Reaction of [Ru(2,2′-bipyridine)(2,2′:6′,2″-terpyridine)Cl]PF₆ (abbreviated to [Ru(bipy)(terpy)Cl]PF₆) with 0.5 equiv of the bidentate ligand L produces the dinuclear complexes [{Ru(bipy)(terpy)}₂(μ-L)](PF₆)₄ (L = 4,4′-bipyridine 1, 1,4-diisocyanobenzene 2 and pyrazine 3) in moderate yields. Treating [Ru(bipy)(terpy)Cl]PF₆ with equal molar of 1,4-diisocyanobenzene affords [Ru(bipy)(terpy)(CNC₆H₄NC)](PF₆)₂ (2a). These new complexes have been characterized by mass, NMR, and UV-Vis spectroscopy, and the structures of 1-3 determined by an X-ray diffraction study. Cyclic voltammetric studies suggest that metal communication between the two ruthenium ions increases from 1 to 2 to 3.     

Synthesis and reactivity with amines of new diiron alkynyl methoxy carbene complexes

The new diiron alkynyl methoxy carbene complexes [Fe₂{μ-CN(Me)(R)}(μ-CO)(CO){C(OMe)CCR′}(Cp)₂]⁺ (R = 2,6-Me₂C₆H₃ (Xyl), R′ = Tol, 3a; R = Xyl, R′ = Ph, 3b; R = Xyl, R′=Buⁿ, 3c; R = Xyl, R′=SiMe₃, 3d; R = Me, R′ = Tol, 3e; R = Me, R′ = Ph, 3f) are obtained in two steps by addition of R′CCLi (R′ = Tol, Ph, Buⁿ, SiMe₃) to the carbonyl aminocarbyne complexes [Fe₂{μ-CN(Me)(R)}(μ-CO)(CO)₂(Cp)₂]⁺ (R = Xyl, 1a; Me, 1b), followed by methylation of the resulting alkynyl acyl compounds [Fe₂{μ-CN(Me)(R)}(μ-CO)(CO){C(O)CCR′}(Cp)₂] (R = Xyl, R′ = Tol, 2a; R = Xyl, R′ = Ph, 2b; R = Xyl, R′ = Buⁿ, 2c; R = Xyl, R′ = SiMe₃, 2d; R = Me, R′ = Tol, 2e; R = Me, R′ = Ph, 2f). Complexes 3 react with secondary amines (i.e., Me₂NH, C₅H₁₀NH) to give the 4-amino-1-metalla-1,3-dienes [Fe₂{μ-CN(Me)(R)}(μ-CO)(CO){C(OMe)CHC(R′)(NMe₂)}(Cp)₂]⁺ (R = Xyl, R′ = Tol, 4a; R = Xyl, R′ = Ph, 4b; R = Me, R′ = Ph, 4c) and [Fe₂{μ-CN(Me)(Xyl)}(μ-CO)(CO){C(OMe)CHC(Tol)(NC₅H₁₀)}(Cp)₂]⁺, 5. The addition occurs stereo-selectively affording only the E-configured products. Analogously, addition of primary amines R′NH₂ (R′ = Ph, Et, Prⁱ) affords the 4-(NH-amino)-1-metalla-1,3-diene complexes [Fe₂{μ-CN(Me)(Xyl)}(μ-CO)(CO){C(OMe)CHC(R)(NHR′)}(Cp)₂]⁺ (R = Ph, 6a; Et, 6b; Prⁱ, 6c). In the case of 6a, only the E isomer is formed, whereas a mixture of the E and Z isomers is present in the case of 6b,c, with prevalence of the latter. Moreover, the two isomeric forms exist under dynamic equilibrium conditions, as shown by VT NMR studies. Complexes 6 are deprotonated by strong bases (e.g., NaH) resulting in the formation of the neutral vinyl imine complexes [Fe₂{μ-CN(Me)(Xyl)}(μ-CO)(CO){C(OMe)CHC(NR)(Tol)}(Cp)₂] (R = Ph, 7a; Et, 7b; Prⁱ, 7c); the reaction can be reverted by addition of strong acids. X-ray crystal structures have been determined for 3a[CF₃SO₃] · Et₂O, 4c[CF₃SO₃], 6a[BF₄] · CH₂Cl₂, 6c[CF₃SO₃] · 0.5Et₂O and 7a · CH₂Cl₂.     

Syntheses, characterization, and DFT investigation of new mononuclear acetonitrile- and chloro-ruthenium(II) terpyridine complexes

A series of mononuclear acetonitrile complexes of the type [Ru(CH₃CN)(L)(terpy)]²⁺ {L = phen (1), dpbpy (3), and bpm (5)}, and their reference complexes [RuCl(L)(terpy)]⁺ {L = phen (2), dpbpy (4), and dpphen (6)} were prepared and characterized by electrospray ionization mass spectrometry, UV-vis spectroscopy, and cyclic voltammograms (CV). Abbreviations of the ligands (Ls) are phen = 1,10-phenanthroline, dpbpy = 4,4′-diphenyl-2,2′-bipyridine, bpm = 2,2′-bipyrimidine, dpphen = 4,7-diphenyl-1,10-phenanthroline, bpy = 2,2′-bipyridine, and terpy = 2,2′:6′,2″-terpyridine. The X-ray structures of the two complexes 2 and 3 were newly obtained. The metal-to-ligand charge transfer (MLCT) bands in the visible region for 1, 3, and 5 in acetonitrile were blue shifted relative to those of the reference complexes [RuCl(L)(terpy)]⁺. CV for all the [Ru(CH₃CN)(L)(terpy)]²⁺ complexes showed the first oxidation wave at around 0.95 V, being more positive than those of [RuCl(L)(terpy)]⁺. The time-dependent-density-functional-theory approach (TDDFT) was used to interpret the absorption spectra of 1 and 2. Good agreement between computed and experimental absorption spectra was obtained. The DFT approach also revealed the orbital interactions between Ru(phen)(terpy) and CH₃CN or Cl⁻. It is demonstrated that the HOMO-LUMO energy gap of the acetonitrile ligand is larger than that of the Cl⁻ one.     

Synthesis of novel mononuclear and dinuclear ruthenium(II) complexes with terpyridine and acetylacetonate ancillary ligands and cyanamide derivative ligands

Several new mononuclear and dinuclear ruthenium(II) complexes - incorporating 2,2′:6′,2″-terpyridine and acetylacetonate as ancillary ligands and phenylcyanamide derivative ligands - of the type [Ru(tpy)(acac)(L)] and [{Ru(tpy)(acac)}₂(μ-L′)] (where tpy = 2,2′:6′,2″-terpyridine, acac = acetylacetonate, L = hmbpcyd = 4-(3-hydroxy-3-methylbutynyl)phenylcyanamide anion (2) and epcyd = 4-ethynylphenylcyanamide anion (3) and L′ = bcpda = bis(4-cyanamidophenyl)diacetylene dianion (4) and bcpea = 9,10-bis(4-cyanamidophenylethynyl)anthracene dianion (5)) were synthesized in a stepwise manner starting from [Ru(tpy)(acac)(Ipcyd)] (1), where Ipcyd = 4-iodophenylcyanamide anion. Tetraphenylarsonium salts of the phenylcyanamide derivative ligands were also prepared. The four complexes have been characterized by UV-Vis, IR, ES-MS, electrochemistry and ¹H NMR. Mononuclear complexes 2 and 3 were further characterized by ¹³C NMR. The single crystal X-ray structure of 2 was determined, it crystallized with one molecule of water with empirical formula of C₃₂H₃₁N₅O₅Ru, in a monoclinic crystal system and space group of P2₁/n with a = 17.642(5) Å, b = 9.634(2) Å, c = 20.063(7) Å, β = 92.65(3)°, V = 3406(2) Å³ and Z = 4. The structure was refined to a final R factor of 0.040. The Ru(III/II) couple of 1-3 appeared around 0.34 V versus the saturated calomel electrode in dimethylformamide and at a slightly higher potential, around 0.36-0.37 V for 4 and 5. Spectroelectrochemical studies were also performed for 4 and 5, no intervalence transition was observed despite all attempts.     

Half-sandwich ruthenium thiocarbonate complexes: Structures of CpRu(PPh3)2SCO2Bu, CpRu(dppe)SCO2Bu and CpRu(PPh3)(CO)SCO2Bu

Thiocarbonate ruthenium complexes of the form CpRu(L)(L′)SCO₂R (L = L′ = PPh₃ (1), 1/2 dppe (2), L = PPh₃, L′ = CO (3); R = Et (a), Buⁿ (b), C₆H₅ (c), 4-C₆H₄NO₂ (d)) have been synthesized by the reaction of the corresponding sulfhydryl complexes, CpRu(L)(L′)SH, with chloroformates, ROCOCl, at low temperature. The bis(triphenylphosphine) complexes 1 can be converted to 3 under CO atmosphere. The crystal structures of CpRu(PPh₃)₂SCO₂Buⁿ (1b), CpRu(dppe)SCO₂Buⁿ (2b), and CpRu(PPh₃)(CO)SCO₂Buⁿ (3b) are reported.     

Artificial photosynthesis based on dye-sensitized nanocrystalline TiO2 solar cells

A new series of amphiphilic heteroleptic ruthenium(II) sensitizers [Ru(H₂dcbpy)(dhbpy)(NCS)₂] (C1), [Ru(H₂dcbpy)(bccbpy)(NCS)₂] (C2), [Ru(H₂dcbpy)(mpubpy)(NCS)₂] (C3), [Ru(H₂dcbpy)(bhcbpy)(NCS)₂] (C4) have been synthesized and fully characterized by UV-Vis, emission, NMR and cyclic voltammetric studies (where dhbpy = 4,4′-dihexyl-2,2′-bipyridine, bccbpy = 4,4′-bis(cholesteroxycarbonyl)-2,2′-bipyridine, mpubpy = 4-methyl-4′-perfluoro-1H,1H,2H,2H,3H,3H-undecyl-2,2′-bipyridine, bhcbpy = 4,4′-Bis(hexylcarboxamido)-2,2′-bipyridine). The amphiphilic amide heteroleptic ruthenium(II) sensitizers, self-assembled on TiO₂ surface from ethanol solution, reveal efficient sensitization in the visible window range yielding ≈80% incident photon-to-current efficiencies (IPCE). Under standard AM 1.5 sunlight, the C4 sensitizer gave 15 mA/cm² short circuit photocurrent density, 0.66 fill factor and an open circuit voltage of 0.75 V, corresponding to an overall conversion efficiency of 7.4%.     

Extended structures of three new coordination polymers based on 1,10-phenanthroline derivatives and 1,4-benzenedicarboxylate mixed ligands: Preparation, structural characterization and properties

Three coordination polymers, namely, [Cd(HOIP)₂(1,4-bdc)] (1), [Cu(HOIP)(1,4-bdc)] (2) and [Cu(PDIP)(1,4-bdc)] (3) (HOIP = 2-(4-hydroxylbenzene) imidazo[4,5-f]1,10-phenanthroline, PDIP = 2-(3-pyridine) imidazo[4,5-f]1,10-phenanthroline, and 1,4-bdc = 1,4-benzenedicarboxylate), have been synthesized under the hydrothermal conditions. All complexes have been characterized by elemental analyses, IR and single-crystal X-ray diffraction. Structural analyses reveal that complex 1 possesses infinite one-dimensional (1D) chain bridged by 1,4-bdc ligands, complexes 2 and 3 both exhibit two-dimensional (2D) (4,4) network structures based on dinuclear [Cu₂O₂] units. However, the weak interactions are different in complexes 1-3. Moreover, the thermal properties of all complexes, fluorescence property of 1, and the electrochemical behavior of 3 are also reported in this paper.     

Effect of pendant arm length and nitrogen donor disposition on the topology of luminescent cadmium phenylenedicarboxylate coordination polymers with bis(pyridylmethyl)piperazine co-ligands

Hydrothermal synthesis has afforded divalent cadmium coordination polymers containing bis(pyridylmethyl)piperazine (bpmp) tethers and either phenylenediacetate (phda) or phenylenedipropionate (phdp) ligands. {[Cd(1,4-phda)(4-bpmp)]·1.5H₂O}_n (1) displays a (4,4)-grid layered structure based on 4-connected {Cd₂O₂} dimeric units. Extension of the pendant arms generated {[Cd(1,4-phdp)(H4-bpmp)](ClO₄)·3.5H₂O}_n (2, phdp = phenylenedipropionate), which possesses a rare (3,6) 2D trigonal lattice based on 6-connected {Cd₂O₂} dimers. Changing the nitrogen donor atom disposition by using 3-bpmp as the nitrogen co-ligand yielded [Cd(1,4-phdp)(3-bpmp)(H₂O)]_n (3), which crystallizes in a 3-fold interpenetrated achiral diamondoid lattice. [Cd(1,3-phda)(4-bpmp)]_n (4) adopts a very similar structure to that of 1. Complexes 1-4 undergo blue-violet luminescence upon exposure to ultraviolet radiation.     

Synthesis, characterization, X-ray structure and in vitro antimycobacterial and antitumoral activities of Ru(II) phosphine/diimine complexes containing the "SpymMe2" ligand, SpymMe2=4,6-dimethyl-2-mercaptopyrimidine

The reaction of cis-[RuCl₂(dppb)(N-N)], dppb = 1,4-bis(diphenylphosphino)butane, complexes with the ligand HSpymMe₂, 4,6-dimethyl-2-mercaptopyrimidine, yielded the cationic complexes [Ru(SpymMe₂)(dppb)(N-N)]PF₆, N-N = bipy (1) and Me-bipy (2), bipy = 2,2′-bipyridine and Me-bipy = 4,4′-dimethyl-2,2′-bipyridine, which were characterized by spectroscopic and electrochemical techniques and X-ray crystallography and elemental analysis. Additionally, preliminary in vitro tests for antimycobacterial activity against Mycobacterium tuberculosis H37Rv ATCC 27264 and antitumor activity against the MDA-MB-231 human breast tumor cell line were carried out on the new complexes and also on the precursors cis-[RuCl₂(dppb)(N-N)], N-N = bipy (3) and Me-bipy (4) and the free ligands dppb, bipy, Me-bipy and SpymMe₂. The minimal inhibitory concentration (MIC) of compounds needed to kill 90% of mycobacterial cells and the IC₅₀ values for the antitumor activity were determined. Compounds 1-4 exhibited good in vitro activity against M. tuberculosis, with MIC values ranging between 0.78 and 6.25 μg/mL, compared to the free ligands (MIC of 25 to >50 μg/mL) and the drugs used to treat tuberculosis. Complexes 1 and 2 also showed promising antitumor activity, with IC₅₀ values of 0.46 ± 0.02 and 0.43 ± 0.08 μM, respectively, against MDA-MB-231 breast tumor cells.     

Two three-dimensional metal-organic frameworks constructed by multiple building blocks of benzenetricarboxylate and bis(imidazole) ligands

Two novel metal-organic frameworks [Zn₃(BTC)₂(bbi)₃]_n (1) (H₃BTC = 1,3,5-benzenetricarboxylate, bbi = 1,1′-(1,4-butanediyl)bis(imidazole)) and{[Zn₃(BTC)₂(bix)₃ · 2.5H₂O]}_n (2) (bix = 1,4-bis(imidazole-1-ylmethyl)benzene) have been hydrothermally prepared and characterized. Analysis of the structure of 1 displays a 3D framework exhibiting a threefold interpenetration net of identical Zn_1.5(BTC)(bbi)_1.5 single frameworks. In the structure of 2, BTC³⁻ and bix build up infinite tubes extending to a 3D non-interpenetrated porous framework. Moderate fluorescent emissions in the solid state at room temperature were observed in both the compounds.     

Cadmium(II) and zinc(II) coordination polymers with mixed building blocks of benzenedicarboxyl and 2,5-bipyridyl-1,3,4-oxadiazole: Syntheses, crystal structures, and properties

Three Cd(II) and Zn(II) coordination polymers, including {[Cd(3-bpo)(mip)(H₂O)](H₂O)₂}_n (1), {[Cd(4-bpo)(hip)(H₂O)](H₂O)₄}_n (2), and {[Zn(4-bpo)(tp)](CH₃OH)}_n (3) were synthesized from the reactions of Cd^II or Zn^II nitrate with mixed organic ligands [3-bpo = 2,5-bis(3-pyridyl)-1,3,4-oxadiazole, H₂mip = 5-methylisophthalic acid, 4-bpo = 2,5-bis(4-pyridyl)-1,3,4-oxadiazole, H₂hip = 5-hydroxylisophthalic acid, H₂tp = terephthalic acid] under the similar layered diffusion condition. The resulting crystalline materials 1-3 were characterized by IR, microanalysis, powder X-ray diffraction (PXRD) techniques. Single-crystal X-ray diffraction indicates a 1-D tubular motif for 1, a 1-D dual-track array for 2, and a 2-D grid-like pattern for 3, constructed via different metal-ligand coordination contacts. Higher-dimensional supramolecular architectures are further assembled in 1-3 via H-bonding and aromatic stacking interactions. In addition, thermal stability and fluorescence of these polymeric complexes were also investigated and discussed.     

Manganese(II) complexes with V-shaped sulfonyldibenzoate: The 3D structures with interpenetrated threefold or tetra-nuclear manganese(II) units

Five Mn^II-sdba coordination polymers with mono-, di-, tri-, tetra-nuclear cores based on the V-shaped 4,4′-dicarboxybiphenyl sulfone (H₂sdba) ligands: [Mn(sdba)(phen)₂(H₂O)]_n·3nH₂O (1), [Mn₂(sdba)₂(μ-H₂O)(py)₄]_n (2), [Mn₃(sdba)₂(Hsdba)₂(2,2′-bipy)₂]_n (3), [Mn₄(sdba)₄(4-mepy)₂(H₂O)₄]_n·2nH₂O (4) and [Mn₄(sdba)₄(bpp)₄(μ-H₂O)₂]_n·0.5nH₂O (5) (phen = 1,10-phenanthroline, 2,2′-bipy = 2,2′-bipyridine, 4-mepy = 4-picoline, bpp = 1,3-bi(pyridine-4-yl)propane) were hydrothermally synthesized and structurally characterized. The M-O-C metal clusters in above complexes act as SBUs, and the V-shaped sdba ligands link the SBUs to generate the novel frameworks. In complexes 1 and 3 their 1D chains are linked into the 2D planes through various hydrogen bonding. Complex 2 displays the 3D structure with interpenetrated threefold, while complexes 4 and 5 both exhibit the 3D structures with the tetra-nuclear Mn₄ units. The magnetic susceptibility studies in the 2-300 K range for these complexes reveal the existence of anti-ferromagnetic exchange interactions between the Mn^II ions.