Vapochromic Properties Research Articles

Metal–organic frameworks based on bipyridinium carboxylate: photochromism and selective vapochromism

Two new photochromic Cd-MOFs based on bipyridinium carboxylate ligands have been synthesized. Interestingly, 1 exhibits vapochromic properties for DEA, possessing rapid, low concentration selectivity and recyclable characteristics for detection of organic gas emissions.

Multi-Stimuli Responsive Donor–Acceptor Tetraphenylethylene Substituted Benzothiadiazoles

In order to understand how the donor (D)/acceptor (A) substituents and their substitution pattern affect the solution and solid-state optical properties, a series of symmetrical and unsymmetrical TPE substituted BTDs 3–8 were designed and synthesized by the Suzuki and Stille coupling reactions. Their solvatochromic, aggregation induced emission (AIE), mechanochromic, and vapochromic properties were studied and compared. The single-crystal X-ray structures of BTDs 5 and 6 are reported. The BTDs 3–8 are highly fluorescent with the tunable emissions. The solvent dependent emission was observed in BTDs 3–8 and their Lippert–Mataga plots show a linear correlation of the Stokes shift with solvent polarity. The emission study in different tetrahydrofuran (THF):water percentages show enhanced emission in aggregates. The BTDs exhibit a reversible multi-stimuli response toward mechanical force, solvent, and heat. The detailed study using single-crystal X-ray, photophysical properties, powder X-ray diffraction, scan...

Vapochromic properties versus metal ion coordination of β-bispyrazolato–copper(ii) coordination polymers: a first-principles investigation

Vapochromic properties of Cu(ii) coordination polymers are explained on the basis of first principles calculations.

Aggregation‐Induced Emission Activity in Iridium(III) Diimine Complexes: Investigations of Their Vapochromic Properties

Two iridium(III) diimine complexes [mono(1,10-phenanthroline)bis(triphenylphosphine)(dihydrido)iridium(III) hexafluorophosphate (1) and mono(1,10-phenanthroline)bis(triphenylphosphine)(hydrido)(chloro)iridium(III) hexafluorophosphate (2)] have been synthesized from a single two-step reaction. The structures of 1 and 2 both adopt distorted octahedral geometries, as established by single-crystal X-ray diffraction. The complexes, upon irradiation with UV light at 365 nm, emit faint light in solution and bright light in the solid state. The ground- and excited-state properties of these complexes were investigated through density functional theory (DFT) and time-dependent DFT calculations. The calculated energies for the transitions from the ground state to the singlet and triplet excited states were close to those determined from the experimental absorption and emission. Their molecular orbitals were also exploited to compute the ground-state dipole moments and redox potentials. Several experiments were performed to demonstrate the “aggregation-induced emission” (AIE) activity of these complexes. AIE was triggered by the restricted intramolecular rotation of the rotating units (phenyls in triphenyphosphines) in these molecules in the solid state. The solid thin films of 1 and 2 exhibit solvent-polarity-dependent vapour-responsive emission properties (vapoluminescent). The rationale for the different emission behavior in the solid state has been thoroughly investigated. The packing diagrams of 1 and 2 show that there is enough space available to accommodate small organic solvent molecules inside the crystal lattices.

Two-dimensional optical waveguiding and luminescence vapochromic properties of 8-hydroxyquinoline zinc (Znq2) hexagonal microsheets.

Two-dimensional (2D) hexagonal microsheets of 8-hydroxyquinoline zinc (Znq2) were synthesized readily via a mixed solvent induced self-assembly method. The 2D optical waveguiding properties of the microsheets have been clearly revealed by both fluorescence microscopy and confocal microscopy. In addition, the reversible vapochromic properties of the microsheets have also been demonstrated when the Znq2 is exposed to HCl and NH3 vapors.

Vapor‐ and Mechanical‐Grinding‐Triggered Color and Luminescence Switches for Bis(σ‐fluorophenylacetylide) Platinum(II) Complexes

Square-planar bis(σ-fluorophenylacetylide) platinum(II) complexes [Pt(Me(3)SiC≡CbpyC≡C-SiMe(3))(C≡CC(6)H(4)F)(2)] (C≡CC(6)H(4)F-2 for 2, C≡CC(6)H(4)F-3 for 3, and C≡CC(6)H(4)F-4 for 4; Me(3)SiC≡CbpyC≡CSiMe(3)=5,5'-bis(trimethylsilylethynyl)-2,2'-bipyridine) were prepared and were characterized by spectroscopic and luminescence studies, and X-ray crystallography. The color and luminescence of crystalline complex 3 is specifically sensitive to CHCl(3) vapor to afford 140-180 nm of luminescence vapochromic redshift, which is useful for specific detection of CHCl(3) vapor. Complex 4 displays selective luminescence vapochromic properties to CH(2)Cl(2) and CHCl(3) vapors with a luminescence vapochromic shift response of ca. 150-200 nm. Interestingly, complexes 2-4 exhibit reversible, and naked-eye perceivable, mechanical stimuli-responsive color and luminescence changes. When solid species 2-4 are crushed gently or ground, the crystalline state is converted to an amorphous phase. Meanwhile, bright yellow-orange luminescence in the crystalline species is converted to dark red under UV light irradiation with 100-160 nm of mechanochromic shift response. A vapochromic or mechanochromic cycle was monitored by dynamic variations in emission spectra and X-ray diffraction (XRD) patterns. The halohydrocarbon vapor- or mechanical-grinding-triggered color and luminescence switches are most likely correlated to a shorted intermolecular Pt-Pt distance as that revealed in vapochromic species 4·0.5 CH(2)Cl(2) by X-ray crystallography, thus leading to an increased contribution from intermolecular Pt-Pt interaction as demonstrated by DTF computational studies.

Synthesis, structure, and magnetic behavior of a pyrazine-bridged Cu(II)/Au(CN)2 complex

The reaction of Cu(ClO4)2 · 6H2O with pyrazine (pz) and KAu(CN)2 in DMSO generates [CuAu(CN)2(pz)(DMSO)2]Au(CN)2 (1). Monoclinic, P21/c: a = 6.8727(2) Å, b = 10.2230(3) Å, c = 14.1923(4) Å, β = 90.0100(10)°. The complex forms 2-D sheets with Cu(II) bridged parallel to the a-axis by pyrazine molecules and parallel to the b-axis by one of the dicyanoaurates (containing Au1). The copper coordination sphere is completed with two O-coordinated DMSO molecules which exhibit short S–Au contacts to Au1 in the adjacent layers. A crystallographically independent ion (containing Au2) provides charge balance and is held in the lattice via Au–Au contacts (Au1–Au2 = 3.436(4) Å). The complex exhibits vapochromic properties. Although stable in dry air at room temperature, green crystals of 1 subjected to a water atmosphere turn pale blue as the DMSO molecules are lost. Other vapors (NH3, PrNH2, py, etc.) generate solvates with a wide variety of colors.

Speciation in solution, solid state spectroscopy and vapochromism of [Pt(trpy)(NCS)]SbF6where trpy = 2,2′:6′,2′′-terpyridine

Treatment of [Pt(trpy)Cl]SbF(6) with AgSCN in a metathesis reaction affords after work-up yellow crystals of [Pt(trpy)(NCS)]SbF(6).CH(3)CN where trpy is 2,2':6',2''-terpyridine. A single crystal structure determination of the solvate shows that the SCN(-) ion is N-bound to the Pt atom, and that the planar cations stack as Pt(2) dimers with a PtPt separation of 3.293(1) A. The crystals rapidly de-solvate under ambient conditions to give a polycrystalline maroon material characterised as [Pt(trpy)(NCS)]SbF(6) (). A (15)N NMR spectroscopic study of a solution of isotopically labeled [Pt(trpy)((15)N(13)CS)]SbF(6) in CD(3)CN shows that both linkage isomers of the SCN(-) ion co-exist in solution with the N-bound isomer dominant, and the S-bound isomer present at a much lower concentration. Compound exhibits temperature dependent (3)MMLCT emission in the solid state; at 280 K the emission maximises at 692 nm, but red-shifts systematically on cooling to reach 762 nm at 80 K. Compound shows vapochromic behaviour that is selective and reversible for vapours of acetonitrile, DMF and pyridine. The colour change is from maroon for to yellow for all three solvates. The emission spectra recorded for the solvates maximise at wavelengths that are all significantly blue-shifted compared to lambda(em)(max) recorded for : the blue-shifts measured at 77 K are 90, 115 and 155 nm for the acetonitrile, DMF and pyridine solvates respectively. The origin of the vapochromic properties of compound is likely to do with the breaking and making of metallophilic PtPt interactions in the solid state.

Cu[Au(CN)2]2(DMSO)2: Golden Polymorphs That Exhibit Vapochromic Behavior

Two polymorphs of an [Au(CN)2]-based coordination polymer, Cu[Au(CN)2]2(DMSO)2, one green (1) and one blue (2), have been identified. In polymorph 1, alternation of five-coordinate Cu(II) and [Au(CN)2]- units generates 1-D chains, while 2-D corrugated sheets are obtained in polymorph 2, which contains six-coordinate Cu(II) centers. Both polymorphs form 3-D networks by virtue of aurophilic interactions of 3.22007(5) A and 3.419(3) A, respectively, and show similar weak antiferromagnetic coupling, but have different thermal decomposition temperatures. They both show vapochromic properties and, importantly, despite their significantly different solid-state structures, the vapochromic behavior of the two polymorphs is essentially identical. Upon solvent exchange, both polymorphs convert to the same Cu[Au(CN)2]2(solvent)x complex (solvent = H2O, CH3CN, dioxane, N,N-dimethylformamide, pyridine, NH3). The Cu[Au(CN)2]2(DMF) and Cu[Au(CN)2]2(pyridine)2 complexes have very similar 2-D square grid structures, comparable to that of 2. The solvent molecules adsorbed by Cu[Au(CN)2]2 bind to the Cu(II) centers, thereby altering the visible spectrum associated with the Cu(II) chromophores and the number and frequency of the nu(CN) as well. The network-stabilizing gold-gold interactions and the flexible coordination sphere of Cu(II) probably facilitate reversible solvent exchange at room temperature.

Vapochromic Properties of Nafion Film Doped with Cationic Dyes

Abstract Protonated Nafion thin film doped with cationic dyes such as flavylium and thionine revealed rapid and vapor-specific color changes (vapochromism) upon exposure to volatile organic compounds. The vapochromic performances were substantially retained after 10 repeated cycles of exposures, implying good reversibility.