Two cobalt(II) metal–organic frameworks based on mixed 1,2,4,5-benzenetetracarboxylic acid and bis(benzimidazole) ligands

Two cobalt(II) metal–organic frameworks constructed from 1,2,4,5-benzenetetracarboxylic acid and flexible bis(5,6-dimethylbenzimidazole) ligands, namely {[Co_1.5(Hbtec)(L1)_1.5(H₂O)₂]·(H₂O)} _n and {[Co(H₂btec)(L2)]·(L2)_0.5(H₂O)₂} _n [L1 = 1,4-bis(5,6-dimethylbenzimidazole-1-ylmethyl)benzene, H₄btec = 1,2,4,5-benzenetetracarboxylic acid, L2 = 1,4-bis(5,6-dimethylbenzimidazole)butane], have been hydrothermally synthesized and characterized by physicochemical and spectroscopic methods and by single-crystal X-ray diffraction. The cobalt atoms present different coordination environments, with trigonal-bipyramidal and octahedral geometries in 1, and a tetrahedral geometry in 2. Complex 1 has a 2D (6,3) wave like layer structure, which is further linked by hydrogen bonding to generate a 3D supramolecular architecture. It is a trinodal (4,4,4)-connected topology with a point symbol of {4²·6·8³}₂{4²·6²·8²}{4³·6³}₂. Complex 2 is a 2D (6,3) honeycomb net, further linked into a 3D supramolecular network via two modes of π–π stacking interactions. The degradation of methyl orange in a Fenton-like process using complexes 1 and 2 as catalysts has been investigated.     

Synthesis, structural features and biological activities of three asymmetric pyridazine–triazole coordination polymers

The complexes [CuL₂Cl₂]_n (1), [CoL₂Cl₂(H₂O)₂]·L (2) and [MnL₂Cl₂(H₂O)₂]·L (3) (L = 3-chloro-6-(1H-1,2,4-triazol-1-yl) pyridazine) were synthesized and characterized by physicochemical and spectroscopic methods. X-ray crystallographic analysis reveals that the Cu(II) center of complex 1 is located in a slightly distorted tetragonal pyramidal environment and bridged by chlorine atoms to generate infinite 1D chains, which are further connected into 2D supramolecular structures by C–H…Cl hydrogen bonds. The Co(II) and Mn(II) atoms in complexes 2 and 3 both have a distorted octahedral coordination sphere, and the crystal lattices include hydrogen bonds and π–π stacking interactions to yield 3D supramolecular frameworks. The antioxidant activities (influence on O₂ ^?? and ^?OH) and antibacterial activities of the ligand L and its three complexes were also investigated.     

Synthesis,crystal structures and photocatalytic properties of four silver(I) coordination polymers based on semirigid bis(pyrazole) and carboxylic acid co-ligands

Four Ag(I) coordination polymers, formulated as [Ag(L1)(tpa)_0.5] _n (1), {[Ag(L2)(ndc)_0.5]·0.5H₂ndc} _n (2), [Ag(L3)_0.5(ndc)_0.5] _n (3) and {[Ag(L3)]·H₃bptc} _n (4) (L1 = 4,4′-bis(pyrazole-1-ylmethyl)-biphenyl, L2 = 4,4′-bis(3,5-dimethylpyrazol-1-ylmethyl)-biphenyl, L3 = 1,4-bis(3,5-dimethylpyrazol-1-ylmethyl)benzene, H₂tpa = terephthalic acid, H₂ndc = 2,6-naphthalenedicarboxylic acid, H₄bptc = 3,3′,4,4′-biphenyltetracarboxylic acid), have been hydrothermally synthesized and structurally characterized. Complex 1 features the rare binodal (4,4)-connected 2D 4,4L10 topological network with a point symbol of {3²·4.6²·7}₂{3²·6²·7²}. Complex 2 has a folded ladder-like chain structure, which is further extended into a 3D supramolecular network via O–H···O hydrogen bonding and π···π stacking interactions. Complexes 3 and 4 both possess 1D zigzag chain structures. Complex 3 is further extended into a binodal (3,4)-connected network with the point symbol of {4.8⁴·10}{6²·8²}₂ by Ag···O weak interactions, while complex 4 is further connected through O–H···O hydrogen bonding and π···π interactions to afford a 2D supramolecular structure. The photoluminescence spectra and photocatalytic properties of these complexes for degradation of methylene blue and methyl orange are reported.     

Crystal structure,spectroscopic and thermal properties of copper(II) and manganese(II) coordination polymers based on triazole-benzoic acid ligands

Two transition metal coordination polymers {[Cu(tba)₂(H₂O)]·2H₂O} _n (1) and {[Mn(Htta)₂(H₂O)₂]·2H₂O} _n (2) {Htba = 3-[1,2,4]triazol-1-yl-benzoic acid, H₂tta = 2-[1,2,4]triazol-1-yl-terephthalic acid} have been synthesized under solvothermal conditions. Both complexes have been characterized by single-crystal X-ray diffraction, X-ray powder diffraction, elemental analysis and FTIR spectroscopy. Complex 1 has a 1-D chain structure in which Cu(II) atoms are doubly bridged by tba^? ligands, which is further stabilized by hydrogen bonding and π–π stacking interactions to give a 3-D supramolecular framework. In complex 2, Mn(II) atoms are doubly bridged by Htta^? ligands to form 1-D chains, which are further connected by intermolecular hydrogen bonds to form a 3-D supramolecular framework. The electronic spectra and thermal behaviors of complexes 1 and 2 are also reported.     

Three cobalt(II) coordination polymers constructed from flexible bis(thiabendazole) and dicarboxylate linkers: crystal structures,fluorescence, and photocatalytic properties

Three Co(II) coordination polymers, namely, {Co(btbb)_0.5(ndc)(H₂O)}_n (1), {[Co(btbb)(bpdc)]·1.5H₂O}_n (2), and {[Co(btbp)₂(3-npa)]·2H₂O}_n (3) (btbb = 1,4-bis(thiabendazole)butane, btbp = 1,3-bis(thiabendazole)propane, H₂ndc = 2,6-naphthalenedicarboxylic acid, H₂bpdc = 4,4′-biphenyldicarboxylic acid and 3-H₂npa = 3-nitro phthalic acid) were synthesized under hydrothermal conditions. Their X-ray crystal structures show that complexes 1 and 2 both have 2D uninodal 3-connected hcb (honeycomb) structures. Complex 1 is further extended into a threefold interpenetrating 3D 4,4-connected mog (moganite) supramolecular architecture with the point symbol of {4.6⁴.8}₂{4².6².8²} by O–H···O hydrogen bonding interactions. Complex 2 shows a 3D supramolecular framework involving π···π stacking interactions. Complex 3 features a uninuclear structure, which is further assembled into an ordered 2D hydrogen-bonded-driven pattern with O–H···O and O–H···N hydrogen bonding interactions. The fluorescence spectra and photocatalytic properties of complexes 1–3 for degradation of methyl orange were investigated.     

Assembly of triorganotin chloride with selenite ligands to macrocyclic,zigzag, helical,and linear structures: syntheses,characterizations, and crystal structures of [R3Sn(O2SeC6H4-4-Et)] n and [R3Sn(O2SeC6H4-2-Et)] n (R = Me,C6H5) complexes

Four new triorganotin(IV) complexes, [R₃Sn(O₂SeC₆H₄-4-Et)]₄ (R = Me 1), [R₃Sn(O₂SeC₆H₄-4-Et)] _n (R = Ph 2), [R₃Sn(O₂SeC₆H₄-2-Et)] _n (R = Me 3; Ph 4) have been synthesized by the treatment of 4-ethylbenzeneseleninic acid, 2-ethylbenzeneseleninic acid, and the corresponding triorganotin(IV) chloride with sodium ethoxide in methanol. All of the complexes were characterized by elemental analysis, FT-IR, NMR (¹H, ¹³C, and ¹¹⁹Sn) spectroscopy, TGA, and X-ray crystallography. Crystal structures show that all of the complexes are generated by the bidentate oxygen atoms and the five-coordinated tin centers with trigonal bipyramid geometry. The structural analyses reveal that complex 1 has a centrosymmetric tetranuclear triorganotin selenite with 16-membered macrocycle, which is formed by trimethyltin and ligand alternate linking. A series of C–H···O and π–π stacking interactions in complex 1 play an important function in the supramolecular aggregation. Complex 3 has two 1D spring-like chiral helical chains and crystallizes in the monoclinic space group P2₁, which is chiral. Complex 2 and 4 are both 1D infinite neutral chain polymers and complex 2 forms a 2D supramolecular framework through intermolecular C–H···O interactions.     

Thermal stabilities and crystal structures of two supramolecular microporous frameworks based on carboxylate-dipyridyl mix-ligands

The mix-ligand system of 5-(4-carboxy-2-nitrophenoxy)isophthalic acid (HСn-H₂Ipa) and dipyridyl-type molecule produces two M(II) porous coordination polymers, namely {[Zn(HCn-Ipa)(Dpe)(H₂O)] · 2H₂O} _n (I) and {[Co(Cn-HIpa)(Dpe)(H₂O)₃] · 2.5H₂O} _n (II) (Dpe = 1,2-di(4-pyridyl) ethylene). Structure determinations reveal that two complexes feature different one-dimensional (1D) polymers assembling into supramolecular microporous frameworks with different thermal stabilities. The 3D supramolecular frameworks of complex I show relatively lower stability, which can be caused by relatively larger porous cavity absent of the strong hydrogen bonds interaction, whereas thick-layer blocks in complex II are cohered further together by H-bonding interactions to form its 3D supramolecular network with relatively higher stability, indicating extraordinarily stable H-bonding systems; CIF files CCDC nos. 966919 (I) and 966920 (II).     

Syntheses and electrochemical properties of three supramolecular architectures based on Keggin silicontungstates and different metal-organic units

Three new compounds [Mn(H₂O)₂(bimb)₂(H₃SiW₁₂O₄₀)₂](bimb)₄ (1), [Zn₂(bimb)₄(H₂O)₄][SiW₁₂O₄₀] (2), and [Ni₂(bimb)₄(H₂O)₄][SiW₁₂O₄₀] (3) (bimb = 1,3-bis(1-imidazoly)benzene) have been synthesized under the same hydrothermal reaction except for tuning the metal cations (Mn²⁺, Zn²⁺, and Ni²⁺). Structural characterizations show that the three compounds possess distinct structural motives. Compound 1 displays a supramolecular one-dimensional (1 D) chain formed by π···π interactions that occur among the almost parallel bimb ligands from adjacent [Mn(H₂O)₂(bimb)₂(SiW₁₂O₄₀)₂] dimers. Compound 2 shows a supramolecular two-dimensional (2D) layer achieved by intermolecular (C–H···O) hydrogen bondings between the Zn₂(bimb)₄ molecular loops and the SiW₁₂ anions. Compound 3 also exhibits a supramolecular 2D layer, but it is different from 2, which is generated by the π···π interactions among adjacent 1D polymeric chains. The distinct structural features of the three compounds suggest that the metal cations should play a significant role in the process of assembly. Additionally, the electrochemical properties of compounds 1–3 have been investigated, and the results indicate that compounds 1–3 possess excellent electrocatalytic activity toward reduction of both iodated and nitrite molecules.     

Synthesis, crystal structures and catalytic properties of Ag(I) and Co(II) 1D coordination polymers constructed from bis(benzimidazolyl)butane

Two metal–organic coordination polymers, {Co(bbbi)_0.5(bm)(Hbtc)} _n (1) and {Ag₂(bbbi)₂(ntp)(H₂O)·4H₂O} _n (2), [bbbi = 1,1-(1,4-butanediyl)bis-1H-benzimidazole, bm = benzimidazole, H₃btc = 1,2,4-trimellitic acid, and H₂ntp = 2-nitroterephthalic acid], have been hydrothermally synthesized and characterized by physico-chemical and spectroscopic methods and single-crystal diffraction. 1 Features a 1D ladder-like chain and is further connected by O–H···O hydrogen bonding interactions to yield a 3D supramolecular architecture. 2 Possesses a 1D infinite zigzag chain connected by bbbi ligands in bis-monodentate mode, which is further extended into a 3D complicated supramolecular network by face-to-face π–π stacking interactions and O–H···O hydrogen bonds. Moreover, both compounds exhibit catalytic properties on degradation of methyl orange in Fenton-like process.     

Effect of carboxylate coligands on the crystal structures of two nickel(II) coordination polymers constructed from a flexible bis(5,6-dimethylbenzimidazole) ligand

Two Ni(II) coordination polymers, [Ni(dmbbbi)(pic)₂·3H₂O] _n (1) and [Ni(dmbbbi)_1.5(pdc)·2H₂O] _n (2) (dmbbbi = 1,1′-(1,4-butanediyl)bis(5,6-dimethylbenzimidazole), Hpic = 2-picolinic acid, H₂pdc = pyridine-2,6-dicarboxylic acid), have been hydrothermally synthesized by self-assembly of nickel chloride with a flexible bis(5,6-dimethylbenzimidazole) ligand and two different pyridine carboxylic acids. The compounds were characterized by physico-chemical and spectroscopic methods and by single-crystal diffraction. Compound 1 possesses 1D ribbon-like chains connected by dmbbbi ligands in bis-bridging mode, which are further extended into a 2D supramolecular network through O–H···O hydrogen bonding interactions between pic anions and lattice water molecules, giving a novel trinodal (3,3,4)-connected topology with the point symbol of (4.6.8)₂(6.8⁴.10). Compound 2 shows a 2D undulant {6³} hexagonal (hcb) network. The structures of the two complexes are further stabilized by intramolecular π···π stacking interactions between the imidazole and N-containing nickel chelate rings. In addition, the fluorescence properties of 1 and 2 have been investigated in the solid state.     

Benzoylacetonate and its fluorinated derivatives as ligands for Co(II) complexes: the effect of the presence of fluorine atoms on the crystal packing

The influence of the introduced fluorine atoms to diketonato backbone exerted on the crystal packing was studied on cobalt(II) bis(4,4,4-trifluoro-1-phenylbutane-1,3-dionato-κ ² O,O′) compounds with pyridine (1), 2,2′-bipyridine (2) and 1,10-phenanthroline (4), and cobalt(II) bis(benzoylacetonato-κ ² O,O′) compound with 2,2′-bipyridine (3). The solid-state structures of 1–4 were determined by single crystal X-ray analysis. The coordination of Co(II) is octahedral in all four compounds. The differences in crystal packing of 1 with regard to the known complexes with non-fluorinated analogue and 4,4,4-trifluoro-1-(4-fluorophenyl)butane-1,3-dionate were observed. Unit cell parameters of 2·½C₇H₈ and 3·½C₇H₈ slightly differ, but they have similar crystal packing dominated by the π–π interactions. Strong π–π interactions and weak C–H···π(arene) and C–F···π(arene) interactions are present in 2–4, while no significant intermolecular interactions are present in 1.     

Metal chelates of N-(2-pyridylmethyl)iminodiacetate(2-) ion (pmda). Part I. Two mixed-ligand copper(II) complexes of pmda with N,N-chelating bases. Synthesis,crystal structure and properties of H2pmda·0.5H2O, [Cu(pmda)(pca)]·3H2O (pca=α-picolylamine) and [Cu(pmda)(Hpb)]·5H2O (Hpb=2-(2′-pyridyl)benzimidazole)

N-(2-Pyridylmethyl)iminodiacetic acid hemi-hydrate (H₂pmda·0.5H₂O) was prepared and characterized by X-ray crystallography (final R1=0.042). The zwitterion H₂pmda^± is intra-stabilized by a trifurcated hydrogen bond. Intermolecular carboxylic-carboxylate hydrogen bonds and the parallel inter-ligand π,π-stacking (3.57(2) Å) between pyridyl rings from pairs of adjacent zwitterions generate 2D frameworks (bi-layers with the carboxyl groups towards the external surfaces and py–pmda rings towards the inside). In the crystal, the bi-layered structures are connected by equivalent hydrogen bonds, which link each water molecule to two symmetry related O-carboxylate atoms from the adjacent external faces of two 2D frameworks. The compounds [Cu(pmda)(pca)]·3H₂O (1) and [Cu(pmda)(Hpb)]·5H₂O (2) were obtained by stoichiometric reaction of Cu₂(CO₃)(OH)₂, H₂pmda·0.5H₂O and α-picolylamine (pca) or 2-(2′-pyridyl)benzimidazole (Hpb), respectively, and characterized by single crystal X-ray diffractometry. Compound 2 was also studied by TG analysis (with FTIR study of the evolved gasses in the pyrolysis), magnetic susceptibility at 80–300 K range, and FTIR, electronic, ESR spectra. In 1 and 2 the copper(II) atom exhibits a distorted octahedral coordination (type 4+1+1) and pmda acts as tripodal tetra-dentate ligand. However, pmda displays different coordination roles. The pmda supplies two N,O-meridional and two trans-apical N(py),O-donors in 1, whereas links the metal by three N,N(py),O-meridional and one O-apical atoms in 2. No π,π-stacking of pyridyl–(pmda) rings is observed in these complexes. The pyridyl–(pca) ring of 1 is not involved in ring–ring stacking interactions, but compound 2 recognizes itself by a roughly anti-parallel π,π-stacking of adjacent Hpb ligands (5.3°, 3.41(2) Å) forming pairs of complex units.     

Isoreticular Linker Substitution in Conductive Metal–Organic Frameworks with Through-Space Transport Pathways

The extension of reticular chemistry concepts to electrically conductive three-dimensional metal–organic frameworks (MOFs) has been challenging, particularly for cases in which strong interactions between electroactive linkers create the charge transport pathways. Here, we report the successful replacement of tetrathiafulvalene (TTF) with a nickel glyoximate core in a family of isostructural conductive MOFs with Mn²⁺, Zn²⁺, and Cd²⁺. Different coordination environments of the framework metals lead to variations in the linker stacking geometries and optical properties. Single-crystal conductivity data are consistent with charge transport along the linker stacking direction, with conductivity values only slightly lower than those reported for the analogous TTF materials. These results serve as a case study demonstrating how reticular chemistry design principles can be extended to conductive frameworks with significant intermolecular contacts.     

A new high-spin iron(III) bis(aqua) complex with the <Emphasis Type="Italic">meso</Emphasis>-tetra(para-chlorophenyl)porphyrin: X-ray crystallography,Hirshfeld surface analysis,magnetic, EPR and electrochemical properties

Chemical preparation of the bis(aqua) iron(III) metalloporphyrin [Fe^III(TClPP)(H₂O)₂](SO₃CF₃)·2(Pnz)·3/4(C₆H₁₂)·2H₂O (TClPP?=?TClPP?=?5,10,15,20-tetra(para-chlorophenyl)porphyrinato and Pnz?=?phenazine) coordination complex (I) was made. The crystal structure of (I) was determined by X-ray single-crystal diffraction and elucidated by Hirshfeld surface approach. Magnetic, spectroscopic and electrochemical properties were also reported and discussed. The mean equatorial distance (Fe–Np) between the iron(III) atom and porphyrin nitrogen atoms is appropriate to a high-spin (S?=?5/2) iron(III) complex. The high-spin state is also confirmed by both magnetic and electron paramagnetic resonance (EPR) spectroscopy data. The repetitive building unit of the crystal structure provides [Fe^III(TClPP)(H₂O)₂]⁺ ion complexes, two non-coordinated Pnz molecules and two water molecules which are interconnected by O–H···O/N/Cl, C–H···O/F/Cl hydrogen bonds, and by C–X···π, C–H···π and π–π stacking intermolecular contacts, forming a 3D supramolecular network. The role and nature of these intermolecular interactions were quantitatively analysed by 3D Hirshfeld surface analysis and associated 2D fingerprint plots. Cyclic voltammetry measurements indicate a one-electron reversible reduction wave with an E_1/2 (Fe(III)/Fe(II) half-potential value of ?0.24 V, which confirms the high-spin S?=?5/2 state of the studied complex.     

Two manganese(II) coordination polymers containing semirigid bis(benzimidazole) ligands: synthesis,crystal structures,and catalytic properties

Two ternary mixed Mn(II) coordination polymers (CPs), namely [Mn(L1)(Hnip)₂] _n (1) and [Mn(H_0.5L2)₂(H_1.5btc)₂] _n (2) (H₂nip = 5-nitroisophthalic acid, L1 = 1, 4-bis(5,6-dimethylbenzimidazol-1-ylmethyl)benzene, H₃btc = 1,3,5-benzenetricarboxylic acid, L2 = 4,4′-bis(benzimidazol-1-ylmethyl)biphenyl), have been synthesized under hydrothermal conditions and structurally characterized. CP 1 exhibits a non-interpenetrated six-connected pcu framework with the point symbol {4¹²·6³}, while CP 2 features a metal-carboxylate loop-like chain, which is further assembled into a 3D supramolecular network via hydrogen bonds and π–π interactions. The thermal stabilities, luminescence, and catalytic properties of both CPs for the degradation of methyl orange in a Fenton-like reaction have also been investigated.     

One- and two-dimensional cobalt(II) coordination polymers derived from flexible bis(benzimidazole) and aromatic carboxylate co-ligands

Two new coordination polymers, formulated as [Co(L1)(btec)_0.5] _n (1) and {[Co(L2)(bdc)]·H₂O} _n (2) (L1 = 1,3-bis(2-methylbenzimidazol-1-ylmethyl)benzene, H₂bdc = 1,3-benzenedicarboxylic acid, H₄btec = 1,2,4,5-benzenetetracarboxylic acid, L2 = 1,3-bis(benzimidazol-1-ylmethyl)benzene), have been hydrothermally synthesized and characterized by physicochemical and spectroscopic methods as well as single-crystal X-ray diffraction. The cobalt atoms present different environments, with a trigonal pyramidal geometry in 1 and a distorted octahedral configuration in 2. Complex 1 shows a 2D (4,4) network linked by L1 and btec^4? anions, giving an uninodal 4-connected sql topology with a point symbol of {4²·6²}, while complex 2 displays a 1D ladder-like chain structure, which is further assembled into a 3D supramolecular architecture via C–H···π hydrogen bonding interactions. The fluorescence properties of both complexes have been investigated in the solid state.     

A highly stable,luminescent and layered zinc(II)-MOF: Iron(III)/copper(II) dual sensing and guest-assisted exfoliation

A highly stable and luminescent metal-organic framework (LMOF) with layered structure, namely, C₆H₄N₅OZn (1) has been successfully achieved and fully characterized by single crystal X-ray diffraction, powder X-ray diffractions, fluorescence titration and thermogravimetry. This blue-light emitting compound 1 exhibit outstanding stability and can detect Fe³⁺ and Cu²⁺ in water specifically, presenting potential application in the field of fluorescent probe technology. Fluorescence titration experiments indicate that the detection of Fe³⁺ ions by 1 is more significant than that of Cu²⁺ ions in terms of K_sv value. Furthermore, guest-assisted exfoliation of layered MOF 1 is efficiently carried out through ether OH hydrogen bond or π···π interactions between the layered host structure and intercalated guest molecules (4,4′-oxybisbenzoic acid and triphenylamine). Tyndal scattering was observed in the suspensions of obtained MOF nanosheets. This study shows that the compound 1 with unique metal ion sensing properties can be applied as a probe material in water pollution treatment field, but also opens up the opportunity for synthesizing luminescent MONs through the “bottom-up” guest intercalation methodology.     

Flexible yet Robust Framework of Tin(II) Oxide Carbodiimide for Reversible Lithium Storage

Metal-organic frameworks (MOFs) can become promising electrode materials for advanced lithium-ion batteries (LIBs), because their loosely packed porous structures may mitigate volume expansion and metal atom aggregation, which occur at the respective metal oxides. However, they suffer from poor electrical conductivity and irreversible structural degradation upon charge/discharge processes, which impede their practical utilization. Herein, we investigate MOF-like Sn₂O(CN₂) as a new electrode material. The conductive yet flexible [N=C=N] linkers are tilted between [Sn₄O] nodes and cross-linked into a porous quasi-layered structure. Such structure offers abundant channels for fast Li-ion transport and tolerance of enormous volume expansion. Notably, anisotropic [N=C=N]²⁻ arrays hardly migrate so that Sn⁰ nanodots are physically separated via robust [N=C=N]²⁻ framework during discharge, thereby effectively preventing the formation of large Sn islands. Owing to the structural advantage, the Sn₂O(CN₂) electrode exhibits an initial Coulombic efficiency as high as ∼80 %. With the addition of graphite as conductive supporter, the electrode provides 978 mAh g⁻¹ at 1.0 A g⁻¹ even after 300 cycles. Such MOF-like carbodiimides hold potential for the advanced electrodes in LIBs and other battery systems.     

Crystal structures, magnetic, dielectric and ferroelectric properties of two copper(II) complexes with m-nitrobenzoic acid

Reactions of CuCl₂, m-nitrobenzoic acid (HNBA) and NaOH with 2,2′-bipyridine (bpy) or 1,10-phenanthroline (phen) in aqueous ethanol afforded two Cu(II) complexes Cu(bpy)(NBA)₂, 1, and [Cu(phen)(H₂O)₂(NBA)](NBA), 2. The monomolecular Cu(bpy)(NBA)₂ moieties are both bridged by hydrogen bonding interactions and interlayer π ^*–π ^*stacking interactions to form a 3D (3,4,6)-connected supramolecular architecture with the Schäfli symbol of (4⁴·6²)(4⁴·6⁶·8⁵)(6³)₂. Complex 2 crystallizes in a noncentrosymmetric space group P2₁ where all molecules show the same orientation along the polar b axis. Preliminary investigations suggest that 2 exhibits ferroelectric hysteresis loops at room temperature with remanent polarization (P _r) of ca. 0.09 μC cm^?2 and coercive electric fields of 2.53 kV cm^?1, respectively. It may be a potential ferroelectric with a relatively large spontaneous polarization (P _s) of 0.22 μC cm^?2. Furthermore, permittivity property measurements reveal a dielectric constant (ε _r) of 6.36. Variable-temperature (2–300 K) magnetic susceptibility measurements showed the presence of weak ferromagnetic interactions between the Cu(II) ions for both 1 and 2.     

Comparable charge transport property based on S…S interactions with that of π-π stacking in a bis-fused tetrathiafulvalene compound

Compact molecular packing with short π-π stacking and large π-overlap in organic semiconductors is desirable for efficient charge transport and high carrier mobility.Thus charge transport anisotropy along different directions is commonly observed in organic semiconductors.Interestingly,in this article,we found that comparable charge transport property were achieved based on the single crystals of a bis-fused tetrathiafulvalene derivative(EM-TTP) compound along two interaction directions,that is,the multiple strong S…S intermolecular interactions and the π-π stacking direction,with the measured electrical conductivity and hole mobility of 0.4 S cm~(-1),0.94 cm~2 V~(-1) s~(-1) and 0.2 S cm~(-1),0.65 cm2 V~(-1) s~(-1),respectively.This finding provides us a new molecular design concept for developing novel organic semiconductors with isotropic charge transport property through the synergistic effect of multiple intermolecular interactions(such as S…S interactions) and π-π stacking.