Semiconducting 2D Copper(I) Iodide Coordination Polymer as a Potential Chemiresistive Sensor for Methanol.

The development of a cost-effective, ultra-selective, and room temperature gas sensor is the need of an hour, owing to the rapid industrialization. Here, a new 2D semiconducting Cu(I) coordination polymer (CP) with 1,4-di(1H-1,2,4-triazol-1-yl)benzene (1,4-TzB) ligand is reported. The CP1 consists of a Cu2 I2 secondary building unit bridged by 1,4-TzB, and has high stability as well as semiconducting properties. The chemiresistive sensor, developed by a facile drop-casting method derived from CP1, demonstrates a response value of 66.7 at 100 ppm on methanol exposure, accompanied by swift transient (response and recovery time 17.5 and 34.2 s, respectively) behavior. In addition, the developed sensor displays ultra-high selectivity toward methanol over other volatile organic compounds , boasting LOD and LOQ values of 1.22 and 4.02 ppb, respectively. The CP is found to be a state-of-the-art chemiresistive sensor with ultra-high sensitivity and selectivity toward methanol at room temperature.

Solvatochromic behaviour of cyclic dithioether-functionalized triphenylamine ligands and their mechano-responsive Cu(I) coordination polymers.

Cu(I)-based coordination polymers (CPs) are known as efficient emissive materials providing an eco-friendly and cost-effective platform for the development of various functional materials and sensors. In addition to the nature of the metal center, organic ligands also play a crucial role in controlling the emissive properties of coordination polymers. Herein, we report on the synthesis of dithiane- and dithiolane-substituted triphenylamine ligands L1 and L2. These ligands were found to be emissive both in the solid state and in solution. In addition, these ligands exhibit solvatochromic behaviour due to the twisted intramolecular charge transfer (TICT) phenomenon. Next, coordination behaviour of these ligands was explored with Cu(I)X salts (X = Br and Cl) and four new 1D coordination polymers [{Cu(µ2-X)2Cu}(µ2-L)]n, CP1 (X = Br, L = L1), CP2 (X = Cl, L = L1), CP3 (X = Br, L = L2), and CP4 (X = Cl, L = L2) were synthesized and crystallographically characterized. The emission behaviour of all the CPs suggests ligand-centered transitions. On mechanical grinding, emission maxima (λem) for CP1 and CP2 were blue-shifted, whereas for CP3 and CP4 red-shifts were observed. All CPs were found to emit at 448 nm with increased intensity after grinding. It is supposed that grinding is responsible for a change in the spatial arrangement (dihedral angles) of the phenyl groups of triphenylamine, causing the observed emission shifts. Furthermore, the higher emission intensity after grinding suggests the occurrence of a similar phenomenon as an aggregation-induced quenching in these CPs.

Ru(II) Complexes with Protic- and Anionic-Naked-NHC Ligands for Cooperative Activation of Small Molecules.

A set of ruthenium(II)-protic-N-heterocyclic carbene complexes, [Ru(NNCH )(PPh3 )2 (X)]Cl (1, X=Cl and 2, X=H) and their deprotonated forms [Ru(NNC)(PPh3 )2 (X)] (1', X=Cl and 2', X=H), in which NNC is a new unsymmetrical pincer ligand, are reported. The four complexes are interconvertible by simple acid-base chemistry. The combined theoretical and spectroscopic investigations indicate charge segregation in anionic-NHC complexes (1' and 2') and can be described from a Lewis pair perspective. The chemical reactivity of deprotonated complex 1' shows cooperative small molecule activation. Complex 1' activates H-H bond of hydrogen, C(sp3 )-I bond of iodomethane, and C(sp)-H bond of phenylacetylene. The activation of CO2 using anionic NHC complex 1' at moderate temperature and ambient pressure and subsequent conversion to formate is also described. All the new compounds have been characterized using ESI-MS, 1 H, 13 C, and 31 P NMR spectroscopy. Molecular structures of 1, 2, and 2' have also been determined with single-crystal X-ray diffraction. The cooperative small molecule activation perspective broadens the scope of potential applications of anionic-NHC complexes in small molecule activation, including the conversion of carbon dioxide to formate, a much sought after reaction in the renewable energy and sustainable development domains.

Crystal structures of 9-[bis-(benzyl-sulfan-yl)meth-yl]anthracene and of cyclo-dodeca-kis-(µ2-phenyl-methane-thiol-ato-κ2 S:S)hexa-palladium(6 Pd-Pd)-anthracene-9,10-dione (1/1).

The first title compound, C29H24S2, L1, represents an example of an anthracene-based functionalized di-thio-ether, which may be useful as a potential chelating or terminal ligand for coordination chemistry. This di-thio-acetal L1 crystallizes in the monoclinic space group P21/c. The phenyl rings of the benzyl groups and that of the anthracene unit form dihedral angles of 49.21 (4) and 58.79 (5)° and the crystal structure displays short C-H⋯π contacts. Surprisingly, when attempting to coordinate L1 to [PdCl2(PhCN)2], instead of the targeted chelate complex [PdCl2(κ2-L1)], a cleavage reaction leads to the formation of the centrosymmetric hexa-nuclear cyclic cluster of composition [Pd6(µ2-SCH2Ph)12] Pd6, or [Pd6(C7H7S)12]·C14H8O2. This tiara-shaped hexa-mer crystallizing in the triclinic space group P consists of six approximately square planar Pd(II)S4 centers, which are inter-connected through twelve µ2-bridging benzyl thiol-ate groups. The Pd⋯Pd contacts range from 3.0892 (2) to 3.1609 (2) Šand can be considered as weakly bonding. The unit cell of Pd6 contains also a co-crystallized anthracene-9,10-dione mol-ecule.

Crystal structure of 2-[bis(benzylsulfanyl)methyl]-6-methoxyphenol.

The title compound, C22H22O2S2, 1, represents an example of an ortho-vanillin-based functionalized di-thio-ether, which could be useful as a potential chelating ligand or bridging ligand for coordination chemistry. This di-thio-acetal 1 crystallizes in the ortho-rhom-bic space group Pbca. The phenyl rings of the benzyl groups and that of the vanillin unit form dihedral angles of 35.38 (6) and 79.77 (6)°, respectively. The crystal structure, recorded at 100 K, displays both weak intra-molecular O-H⋯O and inter-molecular O-H⋯S hydrogen bonding.

1,3-Dithianes as Assembling Ligands for the Construction of Copper(I) Coordination Polymers. Investigation of the Impact of the RC(H)S2C3H6 Substituent and Reaction Conditions on the Architecture of the 0D-3D Networks.

The parent compound 1,3-dithiane (L1) was reacted with CuI providing the 1D coordination polymer [{Cu(µ2-I)2Cu}(µ2-L1)2] n (CP1), an isostructural compound [{Cu(µ2-Br)2Cu}(µ2-L1)2] n (CP2) was isolated upon treatment of CuBr with L1. In contrast, treatment of L1 with CuCl results in the formation of 2D polymeric [{Cu(µ2-Cl)2Cu}(µ2-L1)] n (CP3), in which each sulfur atom acts as a 4-electron donor. The 1D compounds [{Cu(µ2-X)2Cu}(µ2-L2)2] n (CP7, X = Br, and CP8, X = Cl) resulting from treatment of 2-methyl-1,3 dithiane (L2) with CuBr and CuCl are isostructural with their CuI homologue [{Cu(µ2-I)2Cu}(µ2-L2)2] n (CP5), reported previously. Using CuCN, a 2D CP of composition [{Cu(µ2-CN)2Cu}(µ2-L2)2] n (CP9) has been isolated. Complexation of 2-isobutyl-1,3-dithiane (L3) on CuI generates a 2D material [{Cu3(µ3-I)(µ2-I)2(µ2-L3)2}] n (CP10), incorporating the usual trinuclear µ3-I-capped Cu clusters as SBUs, whereas 2D-polymeric compounds [{Cu(µ2-Br)2Cu}(µ2-L3)2] n (CP11) and [{Cu(µ2-Cl)2Cu}(µ2-L3)2] n (CP12) were obtained with CuBr and CuCl. Treatment of 2-Me3Si-1,3-dithiane (L4) with CuX yields the series [{Cu2(µ4-X)(µ2-X)}(µ2-L4)] n (CP13-CP15). With 2-phenyl-1,3-dithiane (L5), the outcome of the reaction with CuI depends on the reaction conditions. Reaction with CuI in MeCN provides a 1D ribbon [{Cu(µ2-I)2Cu}(MeCN)2(µ2-L5)2] n (CP16), whereas treatment of CuI with L5 in hot EtCN yields 2D-polymeric[{Cu3(µ3-I)(µ2-I)2(µ2-L5)2}] n (CP17). A reversible phase transition from triclinic P1̅ to monoclinic P21/ m is observed when recording the structure of CP16 at five different temperatures in the 100-300 K range. Ligand L6 containing a ferrocenyl function at the 2-position was also probed as organometallic dithioether ligand. Reaction of L6 with 1 equiv of CuI produces the 0D dinuclear complex [{Cu(µ2-I)2Cu}(η1-L6)2(MeCN)2] (D1), whereas treatment with 2 equiv of CuI affords the novel 1D CP [{Cu(µ3-I)2Cu}(µ-L6)] n (CP18), in which both S atoms of one L6 molecule span two copper centers of the infinite (CuI) n ribbon. Some selected results of thermal analyses and luminescence measurements are also presented.

Assembly of Coordination Polymers Using Thioether-Functionalized Octasilsesquioxanes: Occurrence of (CuX)n Clusters (X=Br and I) within 3D-POSS Networks.

For the first time, POSS-based coordination polymers (CPs) have been structurally characterized. These CPs were obtained in high yield via self-assembly reactions of thioether-functionalized polysilsesquioxanes with CuI salts under mild conditions. Single crystal analyses revealed the formation of 3D networks incorporating different secondary building units (SBUs) as connection nodes. The nature of the -SAr functionality allows a fine-tuning of the cluster nuclearity, that is, butterfly-shaped Cu2 X2 or closed cubane-type Cu4 I4 cores. As such, the resulting hybrid materials exhibit a combination of high thermal stability arising from the inorganic POSS core along with interesting luminescent properties conferred by the cubane cluster core. Furthermore, the occurrence of channels has been shown crystallographically in the case of the Cu4 I4 cluster containing CP.