Understanding the interactions between the bis(trifluoromethylsulfonyl)imide anion and absorbed CO2 using X-ray diffraction analysis of a soft crystal surrogate.

The selective carbon dioxide (CO2) absorption properties of ionic liquids (ILs) are highly pertinent to the development of methods to capture CO2. Although it has been reported that fluorinated components give ILs enhanced CO2 solubilities, it has been challenging to gain a deep understanding of the interactions occurring between ILs and CO2. In this investigation, we have utilized the soft crystalline material [Cu(NTf2)2(bpp)2] (NTf2‒ = bis(trifluoromethylsulfonyl)imide, bpp = 1,3-bis-(4-pyridyl)propane) as a surrogate for single-crystal X-ray diffraction analysis to visualize interactions occurring between CO2 and NTf2‒, the fluorinated IL component that is responsible for high CO2 solubility. Analysis of the structure of a CO2-loaded crystal reveals that CO2 interacts with both fluorine and oxygen atoms of NTf2‒ anions in a trans rather than cis conformation about the S-N bond. Theoretical analysis of the structure of the CO2-loaded crystal indicates that dispersion and electrostatic interactions exist between CO2 and the framework. The overall results provide important insight into understanding and improving the CO2 absorption properties of ILs.

Nanoparticle chemisorption printing technique for conductive silver patterning with submicron resolution.

Silver nanocolloid, a dense suspension of ligand-encapsulated silver nanoparticles, is an important material for printing-based device production technologies. However, printed conductive patterns of sufficiently high quality and resolution for industrial products have not yet been achieved, as the use of conventional printing techniques is severely limiting. Here we report a printing technique to manufacture ultrafine conductive patterns utilizing the exclusive chemisorption phenomenon of weakly encapsulated silver nanoparticles on a photoactivated surface. The process includes masked irradiation of vacuum ultraviolet light on an amorphous perfluorinated polymer layer to photoactivate the surface with pendant carboxylate groups, and subsequent coating of alkylamine-encapsulated silver nanocolloids, which causes amine-carboxylate conversion to trigger the spontaneous formation of a self-fused solid silver layer. The technique can produce silver patterns of submicron fineness adhered strongly to substrates, thus enabling manufacture of flexible transparent conductive sheets. This printing technique could replace conventional vacuum- and photolithography-based device processing.

Anion-dependent host-guest properties of porous assemblies of coordination complexes (PACs), [Cu(A)2(py)4] (A = PF6, BF4, CF3SO3, and CH3SO3; py = pyridine), based on Werner-type copper(II) complexes in the solid state.

We report the syntheses and crystal structures of novel porous assemblies of coordination complexes (PACs) with/without guest molecules, α-[Cu(A)2(py)4] (α-PAC-2-A (A = PF6, BF4, CF3SO3, and CH3SO3); py = pyridine), γ-{[Cu(PF6)2(py)4]·2guest} (γ-PAC-2-PF6 ⊃ 2guest (guest = acetone and py)), γ-{[Cu(BF4)2(py)4]·2acetone} (γ-PAC-2-BF4 ⊃ 2acetone), and ß-{[Cu(CH3SO3)2(py)4]·2.67H2O} (ß-PAC-2-CH3SO3 ⊃ 2.67H2O). The single-crystal X-ray diffraction analyses of α-PAC-2-A show that α-PAC-2-A have dense packing structures, in which anions of the discrete coordination complexes form weak hydrogen-bonding and anion-π interactions. In contrast, γ-PAC-2-PF6 ⊃ 2guest, γ-PAC-2-BF4 ⊃ 2acetone, and ß-PAC-2-CH3SO3 ⊃ 2.67H2O form guest-including structures with coordination environments around the Cu(II) atoms similar to the α-forms. The vapour adsorption measurements for MeCN and acetone in α-PAC-2-A suggest that the adsorption associated with structural transformations is induced by weak Lewis-base PF6⁻ and BF4⁻ anions covered only with fluorine atoms, which weaken the host-host interactions.

Rational synthesis of a porous copper(II) coordination polymer bridged by weak Lewis-base inorganic monoanions using an anion-mixing method.

The use of divalent Cu(II) ions and an anion-mixing method led to the rational construction of a porous coordination polymer bridged by weak Lewis-base inorganic CF3SO3(-) monoanions.

Porous coordination polymer polymorphs with different flexible pores using a structurally flexible and bent 1,3-bis(4-pyridyl)propane ligand.

Porous coordination polymer (PCP) polymorphs with the formula [Cu(CF3SO3)2(bpp)2]n [1 and 2, where bpp = 1,3-bis(4-pyridyl)propane] have been synthesized and crystallographically characterized, and their distinguishable porous properties have been investigated. 1 was obtained by the removal of guest acetone molecules from one-dimensional PCP {[Cu(CF3SO3)(bpp)2]·CF3SO3·2acetone}n (1⊃2acetone), while 2 was derived from two-dimensional PCP {[Cu(CF3SO3)2(bpp)2]·H2O}n (2⊃H2O) by the loss of guest H2O molecules. The desolvated PCPs 1 and 2 with the same formula [Cu(CF3SO3)2(bpp)2] showed distinguishable structures, suggesting PCP polymorphs. In addition, their adsorption behaviors were completely different: 1 showed adsorption with the structural transformation from closed to open forms, while 2 appeared to expand its framework for only as long as was required for the passage of guest molecules. To the best of our knowledge, PCP polymorphs showing either of two different types of flexible pores are very rare.

Diverse structures and adsorption properties of quasi-Werner-type copper(II) complexes with flexible and polar axial bonds.

The quasi-Werner-type copper(II) complex, [Cu(PF(6))(2)(4-mepy)(4)] (1), in which 4-mepy is the 4-methylpyridine ligand, has flexible and polar axial bonds of Cu-PF(6). Flexibility of the Cu-PF(6) bonds induces diverse and unprecedented guest-inclusion structures, such as {[Cu(PF(6))(2)(4-mepy)(4)][Cu(PF(6))(4-mepy)(4)(acetone)]·PF(6)·4acetone} (γ-1⊃2.5acetone), {[Cu(PF(6))(2)(4-mepy)(4)][Cu(PF(6))(4-mepy)(4)(2-butanone)]·PF(6)·3.5(2-butanone)} (γ-1⊃2.25(2-butanone)), {[Cu(PF(6))(2)(4-mepy)(4)][Cu(PF(6))(4-mepy)(4)(H(2)O)]·PF(6)·4benzene} (γ-1⊃0.5H(2)O·2benzene), and {[Cu(PF(6))(2)(4-mepy)(4)]·2benzene} (γ-1⊃2benzene). Exposure of the dense form, α-1, to benzene vapor affords the benzene-inclusion complex {[Cu(PF(6))(2)(4-mepy)(4)]·2benzene} (γ-1⊃2benzene), all benzene guests of which are easily removed by vacuum drying, reforming guest-free, dense α-1' with smaller sized crystals than α-1. In contrast to α-1, which shows almost no CO(2) adsorption, α-1' adsorbs CO(2) gas with structural transformations, this being the first example that exhibits adsorption of gas in a dense Werner-type complex and a drastic change in adsorption properties depending on the size of the crystals.