Search

International audience; Hybrid organic–inorganic lead-free halide materials have attracted widespread attention due to their applications in the field of optoelectronics. Herein, we synthesized a new binuclear Pd(II) complex templated by 3-bromopropyltrimethylammonium, which undergoes a high-temperature phase transition at about 428 K. Differential scanning calorimetry confirmed this reversible transformation with a large heat hysteresis of 65 K, which depicts a typical first-order phase transition in the compound. The X-ray crystal structure reveals that this material is composed of anionic dimers and organic cations. The complex, [(CH3)3N(CH2)3Br]2Pd2Cl6, crystallizes in the monoclinic system, space group P21/c. The inorganic layer, built up by two crystallographically independent [Pd2Cl6]2− dimer units, is connected to the [(CH3)3N(CH2)3Br]+ organic cations through C–H···Cl hydrogen bonds, which lead to a 3D supramolecular architecture. Each Pd atom is coordinated to two bridging Cl atoms in a slightly distorted square planar geometry. Furthermore, experimental results confirm the semiconducting behavior of [(CH3)3N(CH2)3Br]2Pd2Cl6 with an optical bandgap of ∼2.2 eV. The electric properties were investigated in detail with the study of impedance and AC conductivity. Based on the Elliot theory, the conduction mechanism was deduced with two models: the overlapping polaron model (OLPT) is the right model describing the conduction in phase I, and the correlated barrier hopping model (CBH) describes the conduction in phase II.

International audience; Chiral organic-inorganic halogenometallate hybrids have attracted significant research interest in various fields from optoelectronic to photovoltaic devices. However, to this day the range of available chiral hybrid metal halides still remains limited. In this context, single crystals of organically templated chiral chloropalladate (II), [(R)/(S)-C5H14N2]PdCl4, have been synthesized. Each of the chiral molecular compound consists of (R) or (S)-2-methylpiperazinediium [C5H14N2](2+) cations and [PdCl4](2-) anions. The complexes, [(R)/(S)-C5H14N2]PdCl4 crystallize in the chiral space group P2(1)2(1)2(1) (No. 19), which exhibits the enantiomorphic crystal class 222 (D2). In the crystal structure, the [PdCl4](2-) anions are linked to the organic cations through N-H center dot center dot center dot Cl and C-H center dot center dot center dot Cl hydrogen bonds to form cation-anion-cation molecular units. The incorporation of a protonated (R) or (S)-2-methylpiperazine cations into the same inorganic halide systems leads to similar properties. The thermal analysis, optical and electric properties of [(R)-C5H14N2]PdCl4 (1) compound have been studied. The title compound [(R)-C5H14N2]PdCl4 (1) reveals thermal stability up to ca. 450 K. Besides, [(R)-C5H14N2]PdC(l)4 (1) shows semi-conducting behavior with an optical band gap of similar to 3.64 eV. The electric properties are investigated and the equivalent circuit is chosen and confirms the contribution of the grain and grain boundaries. The values of AC conductivities (10(-6) Omega(-1)cm(-1)) confirm the gap energy and the semiconducting character of the R enantiomer. The value of activation energy is determinated and shows the ionic conduction type. Such a chiral hybrid metal halide offers a viable strategy for the targeted design and synthesis of non-centrosymmetric metal halide materials for optoelectronic applications.

International audience; Hybrid halide perovskite-like semiconductors are attractive materials for various optoelectronic applications, from photovoltaics to smart devices. Here, two new one-dimensional palladium halides, [C9H16N2]PdCl4 (1) and [C9H16N2]PdBr4 (2) showing electrical and optical properties were prepared by reaction of 2,4,6-trimethyl-m-phenyl-enediamine with PdX2 (X ​= ​Cl, Br) in the corresponding concentrated halogen acids HX.Single-crystal X-ray diffraction analysis reveals that compounds [C9H16N2]PdX4(X ​= ​Cl,Br) belong to isostructural phases and crystallize in the orthorhombic system with non-centrosymmetric space group Pmc21. The basic unit of the crystal structure in each compound is composed of an independent [PdX4]2- anion charge balanced by a [C9H16N2]2+ cation. Remarkably, the central Pd(II) atom is coordinated by five halogen atoms PdX5 forming a distorted square-pyramidal coordination geometry. These hybrid compounds present good thermal stability up to 500 ​K. The DSC and electric measurements show that no phase transition occurs in the compounds over the temperature range 300–400 ​K. Optical absorption measurements suggest that the two hybrids Pd(II)-based metal halides have a narrow optical band gap (Eg) of ∼3.26 ​eV (X ​= ​Cl) and ∼2.98 ​eV (X ​= ​Br) which makes them promising materials in optoelectronic devices. Besides, compounds exhibit broadband green emission excited by UV light at room temperature. The electrical study shows the contribution of the grain and grain boundary in the conduction of these materials and confirms the optical result where the conductivity of the compound (1) is higher than the compound (2). The variation of the conductivity of grain confirms the activation energies calculated for the two regions. © 2022 Elsevier Inc.

International audience; The molecular organic-inorganic hybrid halogenometallate [(R)-C9H14N](3)[CuBr4]center dot Br has been synthesized by a slow evaporation method. The single-crystal X-ray diffraction experiment evidences that [(R)-C9H14N](3)[CuBr4]center dot Br crystallizes in the monoclinic system with the non-centrosymmetric space group P2(1) at T = 150K. The compound displays a zero-dimensional (0D) structure which consists in three chiral [(R)-C9H14N](+) cations, one anionic [CuBr4](2-) and free Br- ion. The structure analysis reveals that the Cu(II) has an intermediate geometry between regular tetrahedron (T-d) and square planar (D-4h). In the crystal structure, the cations and anions are arranged in alternating stacks which are interconnected via hydrogen bonding contacts N-H center dot center dot center dot Br. This hybrid compound presents good thermal stability up to 370 K. The DSC and electric measurements show that no phase transition occurs in the compound over the temperature range 223-423 K. Optical absorption measurements suggest that [(R)-C9H14N](3)[CuBr4]center dot Br has a narrow direct optical band gap (E-g) of similar to 2.15 eV which makes it a promising material in optoelectronic devices.

International audience; A new Co(II)-based organic-inorganic hybrid compound, [(CH3)(3)N(CH2)(2)Br](2)[CoBr4], was synthesized by slow evaporation at room temperature. The compound was characterized by single crystal X-ray diffraction, thermal analysis, optic and dielectric measurements. [(CH3)(3)N(CH2)(2)Br](2)[CoBr4] belongs to the monoclinic P2(1)/c space group at 150K. Molecular structure of the compound consists of discrete [CoBr4](2-) anions and (2-bromoethyl) trimethylammonium cations linked together via non-covalent interactions including C-H center dot center dot center dot Br hydrogen bonding and weak halogen center dot center dot center dot halogen interactions which lead to a three-dimensional supramolecular network. The thermal analysis reveals a reversible phase transition at 366/337 K upon heating/cooling respectively, which is giving rise to a thermal hysteresis of similar to 26 K. In addition, the UV/Vis optical spectrum indicates that the material has an indirect band gap of 3.7 eV which can be used in the application of the semiconductor materials. The electrical properties as a function of frequency and temperatures were studied and confirmed the phase transition showed in the thermal analysis. The equivalent circuit was determined to separate grain and grain boundaries response and determine the grain resistivity. The modulus studies confirm the presence of grain and grain boundaries. The AC conductivity was analyzed by Jonscher power law and showed that the conduction mechanisms are well described by the small polaron tunnel (SPT) and overlapping large polaron tunneling (OLPT) models in the phases I and II, respectively. The variation of sigma(g), f(p) and sigma(dc) from the simulation of Nyquist diagram, Modulus and AC conductivity proves the transition in the DSC and allows to determinate the activation energies for the two phases. These results will provide positive clues to explore the semiconductor and electrical properties of hybrid halogenometallate complexes. (C) 2020 Elsevier B.V. All rights reserved.

International audience; A new layered perovskite-type organic-inorganic hybrid compound [Cl-(CH2)(2)-NH3](2)[CuCl4] (1), in which 2-chloroethylammonium cation occupies the space enclosed by the CuCl6 octahedra, has been successfully synthesized. It is found that the compound exhibits the semiconducting properties with the optical band gap equal to 1.98 eV, confirmed by AC conductivity measurements, which varies between 10(-5) and 10(-4) omega(-1) m(-1). Also, the low activation energy at low temperatures (0.26 eV) can indicate the electronic conduction of this material. Compound (1) displays phase transitions at T-1 = 281 K and T-2 = 380 K, confirmed by DSC, electrical and dielectric measurements. Single-crystal X-ray diffraction data at variable temperatures reveal that symmetry-breaking occurs from P2(1)/c (at 296 K > T-1) to P-1 (at 150 K < T-1), originating directly from the [Cl-(CH2)(2)-NH3](+) cation conformational changes and the distortions of CuCl64- octahedra caused by the Jahn-Teller effect in the inorganic layers. Meanwhile, organic 2-chloroethylammonium moieties display some boat-like conformation below T-1, which transforms to a chair-like structure above T-1. This study paves the pathway to explore new lead-free hybrid perovskites with targeted properties for thermoelectric, supercapacitors, batteries, environmentally friendly processing and semiconductor applications.

International audience; Hybrid inorganic-organic perovskites attracted increasing attention because of variety of their applications in the fields of photovoltaics, photoelectronics and switchable dielectric devices. Diverse molecular functional materials can be assembled by modifying the length of the organic components and inorganic framework dimensionality and, thus, they might be promising candidates to obtain phase-transition materials. In this study, we present a new hybrid perovskite-like compound, (ClC2H4NH3)2CuBr4 (I), which follows the two-dimensional inorganic frameworks of the corner-sharing CuBr6 octahedra. Strikingly, compound (I) displays a dielectric phase transition at around 275 ​K, changing from the non-centrosymmetric space group of Pc (LT phase) to centrosymmetric P21/a (HT phase) upon heating. The crystal structure analyses reveal that the unusual thermally activated conformation change of the 2-chloroethylammonium cations and distortions of CuBr6 4− network in the inorganic layers afford the driving force to the phase transition. Moreover, the Jahn−Teller distortion introduces elongation of coordination bonds in the inorganic planes, which confers higher flexibility to the structure. Compound (I) displays phase transitions at T1 ​= ​270 ​K and T2 ​= ​323 ​K, confirmed by DSC measurements. In addition, the UV/Vis optical spectrum indicates that (I) has an indirect band gap of 1.47 ​eV. This finding may extend the application of 2D layered lead-free hybrid perovskite-type materials to the field of photovoltaic as the photo absorber layer of solar cells.

International audience; Two organic-inorganic hybrid compounds [(CH3)(3)N(CH2)(2)Br](2) [(MBr4)-Br-II] (M = Cu, Zn); ((2-bromoethyl) trimethylammonium cations [Br(CH2)(2)N(CH3)(3)](+)) were successfully synthesized with slow evaporation conditions. The structures of the two compounds were determined using single-crystal X-ray diffraction. These materials crystallize in the monoclinic system, space group P2(1)/c. In the molecular arrangement, the [(MBr4)-Br-II](2-) anions are linked to the organic cations through C-H center dot center dot center dot Br hydrogen bonds to form cationanion-cation molecular units, giving a three-dimensional network. The phase transitions, electric and optical properties of [(CH3)(3)N(CH2)(2)Br](2) [CuBr4] (1) and [(CH3)(3)N(CH2)(2)Br](2) [ZnBr4] (2) were carefully characterized. Based on these results, both compounds underwent phase transitions at T-1 = 368 K and T-2 = 385K for (1) and at T-1 = 283K, T-2 = 330K, T-3 = 368K and T-4 = 402K for (2). The optical and electrical properties allow to determinate the gap energy and to characterize the phase transitions. These studies pave the pathway to explore new types of high-phase transition materials with targeted properties for electric and semiconductor applications.

International audience; A new organic–inorganic hybrid compound [C7H16N2][ZnCl4] was synthesized by hydrothermal method and characterized by single-crystal X-ray diffraction, IR and Raman spectroscopy, optical absorption, differential scanning calorimetry and dielectric measurements. Single crystal diffraction results showed that [C7H16N2][ZnCl4] crystallizes in the monoclinic system, space group P21/c at room temperature. In the molecular arrangement, the tetrachlorozincate anions are connected to organic cations through N-H...Cl hydrogen bonds. The Raman and IR analyses confirm the presence of the organic groups and the anionic entities. UV–Visible absorption spectrum revealed the energy of the optical band gap. DSC measurements indicated that [C7H16N2][ZnCl4] undergoes three sequential phase transitions at 287, 338 and 356 K. The dielectric study proved the ferroelectric properties below the 338K and indicates their classical character for this compound. The analysis of Nyquist plots revealed the contribution of the bulk mechanism and the grain boundaries.

(R)-(+)-3-aminoquinuclidine was used in the synthesis of [(R)-C7H16N2][CuCl4] (1) and [(R)-C7H16N2][CuBr4] (2), which both contain similar [CuX4]2- anions (X = Cl or Br). The structures of the two compounds were determined using single-crystal X-ray diffraction. The use of enantiomerically pure sources of (R)-C7H14N2 forces crystallographic noncentrosymmetry. These materials crystallize in the chiral space group P212121 (No. 19), which exhibits the enantiomorphic crystal class 222 (D2). In the molecular arrangement, the [CuX4]2- anions are linked to the organic cations through N H … X and C H … X hydrogen bonds to form cation-anion-cation molecular units, which are held together by means of offset face-to-face interactions giving a three-dimensional network. Thermal stability of the crystals was ascertained by TG measurement. Compounds (1) and (2) display several phases transition with higher transition temperature at T = 100 °C. The Kurtz and Perry powder method using Nd:YAG laser shows that their second harmonic generation (SHG) efficiencies are about 0.81 and 0.82 times as large as that of KH2PO4 (KDP), respectively. Such a chiral hybrid metal halides skeleton could provide a new platform for future engineering in the areas including information storage, light modulators and optoelectronic functionalities.

International audience; The directed synthesis of non-centrosymmetric copper (II) bromo-complex has been achieved through the use of homochiral organic molecule. Reaction containing (S)-(-)-3-aminoquinuclidine, CuBr2, HBr and H2O were subjected to mild hydrothermal conditions, resulting in the growth of single crystals of [(S)-C7H16N2][CuBr4]. The compound crystallizes in the non polar space group P2(1)2(1)2(1)(No. 19), which exhibits the enantiomorphic crystal class 222 (D-2). In the crystal structure, the tetrabromocuprate(II) anion is connected to three organic cations through N-H center dot center dot center dot Br hydrogen bonds to form cation-anion-cation molecular units, which are held together by means of offset face-to-face interactions to give one-dimensional chains. DSC measurements indicated that the compound [(S)-C7H16N2][CuBr4] underwent a reversible phase transition at 80 degrees C. [(S)-C7H16N2][CuBr4] is more than 1.2 times as efficient as KDP in second harmonic generation; making it a potentially attractive material for non-linear optical applications. The synthesized product was also screened for in vitro antioxidant and antimicrobial activities, while showing favorable antioxidant activities against DPPH as well as the discoloration of beta-carotene. (C) 2018 Elsevier B.V. All rights reserved.

Single crystals of [(R)-C5H14N2][Cu(SO4)2(H2O)4]·2H2O (1) were grown through the slow evaporation of a solution containing H2SO4, (R)-C5H12N2 and CuSO4·5H2O. These crystals spontaneously transform to [(R)-C5H14N2]2[Cu(H2O)6](SO4)3 (2) over the course of four days at room temperature. The same single crystal on the same mounting was used for the determination of the structure of (1) and the unit cell determination of (2). A second single crystal of the transformed batch has served for the structural determination of (2). Compound 1 crystallizes in the noncentrosymmetric space group P21 (No. 4) and consists of trimeric [Cu(SO4)2(H2O)4]2− anions, [(R)-C5H14N2]2+ cations and occluded water molecules. Compound 2 crystallizes in P21212 (No. 18) and contains [Cu(H2O)6]2+ cations, [SO4]2− anions and occluded water molecules. The thermal decompositions of compounds 1 and 2 were studied by thermogravimetric analyses and temperature-dependent X-ray diffraction.

A series of double dihydromethylpiperazinediium metallic sulfates 1-7 [H(2)mpz]M(II)(SO(4))(2)·nH(2)O (mpz = 2-methylpiperazine, C(5)H(12)N(2)) are prepared by slow evaporation using a racemic (R/S)-mpz (for 1, 2) or enantiopure R-mpz (for 3), S-mpz (for 4-7) and sulfates of Cu(II) (for 5), Fe(II) (for 1, 4), Co(II) (for 7) and Zn(II) (for 2, 3, 6), and characterized by infrared spectroscopy, elemental analysis and single crystal X-ray diffraction. The [M(II)(H(2)O)(6)](2+), [(R/S)-H(2)mpz](2+), [(R)-H(2)mpz](2+) or [(S)-H(2)mpz](2+) cations and 2SO(4)(2-) anions are linked together via two types of hydrogen bonds, Ow-Hw···O and N-H···O, leading to supramolecular arrangements. The use of the racemic 2-mpz provides alternatives in crystallization: a centrosymmetric structure where the enantiomers are related by an appropriate crystallographic symmetry operation or one where the enantiomers occupy the same crystallographic position, generating disorder. Compounds 1-7 act as diastereoselective catalysts for the nitroaldol (Henry) reaction. The diastereoselectivity can be regulated from exclusive threo to exclusive erythro isomer preparation with typical yields of 50-99%, depending on the catalyst and the substrate used.

The crystal structure of copper sulfate templated by 2-methylpiperazine, (C5H14N2)[Cu(SO4)2(H2O)4] · H2O, was investigated using single crystal X-ray diffraction data. At room temperature, it crystallises in the monoclinic P21/n space group with the following unit-cell parameters: a = 6.9153(1), b = 23.1295(3), c = 10.4472(1) A, β = 104.227(1)°, V = 1619.75(4) A3 and Z = 4. The CuII cation adopts a slightly distorted octahedral geometry, arising from four water molecules and two sulfate tetrahedra leading to the formation of [Cu(SO4)2(H2O)4] units. The structure consists of isolated [Cu(SO4)2(H2O)4]2− anions, 2-methylpiperazinediium cations (C5H14N2)2+ and water molecules connected by a three-dimensional hydrogen-bond network. The thermal decomposition of the precursor, studied by thermogravimetry and temperature-dependent X-ray powder diffraction, proceeds through four stages giving rise to the copper oxide.

In the title salt, C10H28N44+·4HSO4−, the cation lies about an inversion center. In the crystal, O—H...O and N—H...O hydrogen bonds connect the anions and cations, forming a three-dimensional network.

International audience; Two new non-centrosymmetric copper sulfates are synthesized under slow evaporation conditions through the use of enantiomorphically pure sources of either (R)-2-methylpiperazine or (S)-2-methylpiperazine. Both crystallize in the non-centrosymmetric P2(1) space group, crystal data for [(R)-C5H14N2][Cu(H2O)(6)](SO4)(2) (I), a = 6.5276(2) , b = 11.1955(3) , c = 12.4559(4) , beta = 101.196(2)A degrees, Z = 2, V = 892.95(5) (3) and [(S)-C5H14N2][Cu(H2O)(6)](SO4)(2) (II), a = 6.5188(2) , b = 11.1786(2) , c = 12.4365(3) , beta = 101.205(1)A degrees, Z = 2, V = 888.99(4) (3). The three-dimensional structure networks for these compounds consist of isolated [Cu(H2O)(6)](2+) and [(R)-C5H14N2](2+) or [(S)-C5H14N2](2+) cations and SO (4) (2-) anions linked only by hydrogen bonds. The Cu atom is in a slightly distorted octahedral coordination environment. The crystal packings are influenced by cation-to-anion N-HaEuro broken vertical bar O and OW-HaEuro broken vertical bar O hydrogen bonds leading to an open framework structures.

A series of noncentrosymmetric metal sulfates [R-C 5 H 14 N 2 ][M II (H 2 O) 6 ](SO 4 ) 2 and [S-C 5 H 14 N 2 ][M II (H 2 O) 6 ](SO 4 ) 2 (M II = Mn (1, 2), Fe (3, 4), Co (5, 6) and Ni (7, 8)) have been synthesized by slow evaporation conditions through the use of enantiomorphically pure sources of either R-2-methylpiperazine (R)-C 5 H 12 N 2 or S-2-methylpiperazine (S)-C 5 H 12 N 2 . These materials crystallize in the polar, noncentrosymmetric space group P 2 1 (No. 4), crystal class 2 ( C 2 ). Isolated [M II (H 2 O) 6 ] 2+ , [(R)-C 5 H 14 N 2 ] 2+ or [(S)-C 5 H 14 N 2 ] 2+ cations and (SO 4 ) 2− anions linked together via two types of hydrogen bonds, O w –H w ⋯O and N–H⋯O, from which supramolecular structures are formed. The use of single enantiomer of either R-2-methylpiperazine or S-2-methylpiperazine precludes inversion symmetry within the crystal lattices and forces crystallization in noncentrosymmetric structures. Compounds 1 – 8 were characterized using single crystal X-ray diffraction, infrared spectroscopy and thermal analyses. The structural arrangements and the intermolecular interactions such as hydrogen-bonding are discussed.

International audience; A series of novel organically templated metal sulfates, [C(5)H(14)N(2)][M(II)(H(2)O)(6)](SO(4))(2) with (M(II) = Mn (1), Fe (2), Co (3) and Ni (4)), have been successfully synthesized by slow evaporation and characterized by single-crystal X-ray diffraction as well as with infrared spectroscopy, thermogravimetric analysis and magnetic measurements. All compounds were prepared using a racemic source of the 2-methylpiperazine and they crystallized in the monoclinic systems, P2(1)/n for (1, 3) and P2(1)/c for (2,4). Crystal data are as follows: [C(5)H(14)N(2)][Mn(H(2)O)(6)](SO(4))(2), a = 6.6385(10) Å, b = 11.0448(2) Å, c = 12.6418(2) Å, β = 101.903(10)°, V = 906.98(3) Å(3), Z = 2; [C(5)H(14)N(2)][Fe(H(2)O)(6)](SO(4))(2), a = 10.9273(2) Å, b = 7.8620(10) Å, c = 11.7845(3) Å, β = 116.733(10)°, V = 904.20(3) Å(3), Z = 2; [C(5)H(14)N(2)][Co(H(2)O)(6)](SO(4))(2), a = 6.5710(2) Å, b = 10.9078(3) Å, c = 12.5518(3) Å, β = 101.547(2)°, V = 881.44(4) Å(3), Z = 2; [C(5)H(14)N(2)][Ni(H(2)O)(6)](SO(4))(2), a = 10.8328(2) Å, b = 7.8443(10) Å, c = 11.6790(2) Å, β = 116.826(10)°, V = 885.63(2) Å(3), Z = 2. The three-dimensional structure networks for these compounds consist of isolated [M(II)(H(2)O)(6)](2+) and [C(5)H(14)N(2)](2+) cations and (SO(4))(2-) anions linked by hydrogen-bonds only. The use of racemic 2-methylpiperazine results in crystallographic disorder of the amines and creation of inversion centers. The magnetic measurements indicate that the Mn complex (1) is paramagnetic, while compounds 2, 3 and 4, (M(II) = Fe, Co, Ni respectively) exhibit single ion anisotropy.

International audience; The directed synthesis of a new organically templated copper sulfate has been achieved through the use of chiral organic amine. Reaction containing S-2-methylpiperazine, CuSO(4)center dot 5H(2)O, H(2)SO4 and H(2)O were subjected to the slow evaporation conditions, resulting in the growth of single crystals of [(S)-C(5)H(14)N(2)][ Cu(SO(4))(2)(H(2)O)(4)]center dot(H(2)O)(2). At room temperature, it crystallises in the non-centrosymmetric space group P2(1), Z = 2, a = 7.5583(5), b = 10.1721(6), c = 10.7974(7) angstrom, beta = 94.425(4)degrees and V = 827.67(9) angstrom(3). The structure consists of trimeric units [Cu(SO(4))(2)(H(2)O)(4)](2) , [(S)-C(5)H(14)N(2)](2+) cations and free water molecules, donating hydrogen bonds that stabilize the three-dimensional structure and filling space. The title compound undergoes a reversible phase transition of first-order, which is detected by differential-scanning calorimetry at 347.2 K in the heating cycle and at 318.9 K in the cooling cycle. The evolution of the dielectric constant as a function of frequency and temperature revealed this transition to be ferro-paraelectric. Thermogravimetric analyses indicate that its decomposition proceeds through three stages giving rise to the copper oxide.