The influence of the ligands on the catalytic activity of a series of RhI complexes in reactions with phenylacetylene: Synthesis of stereoregular poly(phenyl) acetylene

The catalytic activity of a series of [Rh L-L chel]X complexes, in which we have varied the unsaturated ligand [L-L = cis, cis-cycloocta 1,5-diene(cod) or 2,5-norbornadiene(nbd) the nitrogen chelating ligand [chel = 2,2′-bipyridine(bipy), 2,2′-dipyridylamine(dipyam), 2,2′-bipyrazine (bipz), 4,4′-dimethyl-2,2′-bipyridine (4,4′-Me₂bipy)] and the counter ion [X = PF₆, ClO₄, BPh₄], has been examined in reactions with phyenylacetylene (PA). The catalytic behaviour of the [Rh(cod)Cl₂],tmeda (tmeda = N,N,N′,N′tetramethylethylendiamine), [Rh(cod)Cl₂],teda] (teda = triethylendiamine), of the dimer [Rh(cod)Cl]₂, and the use of NaOH as cocatalyst in different reaction conditions was also examined. The influence of the ligands on the catalytic activity of these Rh^I complexes is discussed. ¹H and ¹³C NMR spectra have shown that highly stereoregular polyphenylacetilene can be obtained. Conditions for homogeneous doping of PPA, to obtain materials whose conductivity varies over 10–11 magnitude orders, are proposed. The stability of the doped polymers is also discussed.     

Synthesis and characterization of poly(1-benzoylsemicarbazide) and poly(1,3,4-oxadiazole amine) from 2-(p-aminophenyl)-1,3,4-oxadizolin-5-one via ring-opening

A novel thermally stable and semiconducting polyheterocycle, poly(1,3,4-oxadiazole amine), was synthesized from 2-(p-aminophenyl)-1,3,4-oxadiazolin-5-one via ring-opening. The polymer is a new class of ordered alternating copoly(aniline) containing 1,3,4-oxadiazole heterocyclic units. The polymer is highly thermally stable and exhibits no weight loss up to 370°C in air. Its electric conductivity is less than 10⁻¹⁰ S · cm⁻¹ at ambient temperature, but markedly increases to 6,5 · 10⁻⁷ S · cm⁻¹ upon doping with iodine.     

Study of carbonaceous clusters in irradiated polycarbonate with UV–vis spectroscopy

The formation of carbonaceous clusters in ion‐irradiated polymer films was investigated extensively. Information about these clusters may be obtained with ultraviolet–visible (UV–vis) spectroscopy. The optical band gap (E_g), calculated from the absorption edge of the UV spectra of these polymers, can be correlated to the number of carbon atoms (N) in a cluster with the modified Tauc equation. The structure of the cluster is also related to E_g; for example, a six‐membered‐benzene‐ring‐type structure has an E_g of ≈5.3 eV, whereas a buckminsterfullerene‐type structure has an E_g of ≈4.9 eV. These clusters are responsible for the electrical conductivity in these films. In this work, polycarbonate films (20 μm thick) were irradiated with 45‐MeV Li ions at fluences of 1 × 10¹² to 1 × 10¹³ cm⁻² and were characterized with UV–vis spectroscopy and impedance measurements. The E_g values, calculated from the absorption edge in the 280–315‐nm region with the Tauc relation, varied from 4.39 to 4.35 eV for the pristine and various irradiated samples, respectively. The cluster size showed a range of 60–62 carbon atoms per cluster. The sheet conductivity (σ_dc) and loss (tan δ) values of 10⁻¹⁶ Ω⁻¹cm⁻¹ and 10⁻³ for the pristine sample changed to 10⁻¹⁵ Ω⁻¹cm⁻¹ and 10⁻², respectively, for the irradiated samples. This increase in the values of σ_dc and tan δ may be correlated to the increase in the size of the carbonaceous clusters. This study provides insight into the mechanism of electrical conductivity in irradiated polymers. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1589–1594, 2000     

High-Temperature Proton Conduction in LaSbO4

Lanthanum orthoantimonate was synthesized using a solid-state synthesis method. To enhance the possible protonic conductivity, samples with the addition of 1 mol % Ca in La-site were also prepared. The structure was studied by the means of X-ray diffraction, which showed that both specimens were single phase. The materials crystallized in the space group P2₁/n. Dilatometry revealed that the material expanded non-linearly with the temperature. The nature of this deviation is unknown; however, the calculated linear fraction thermal expansion coefficient was 9.56×10⁻⁶ K⁻¹. Electrical properties studies showed that the material is a proton conductor in oxidizing conditions, which was confirmed both by temperature studies in wet in dry air, but also by the H/D isotope exchange experiment. The conductivity was rather modest, peaking at the order of 10⁻⁶ S cm⁻¹ at 800 °C, but this could be further improved by microstructure and doping optimization. This is the first time protonic conductivity in lanthanum orthoantimonates is reported.     

Temperature dependence of the rate constants of the reactions of oxygen atoms with 1-pentene, 1-hexene,cis-2-pentene,and trans-2-pentene

The kinetics of the reactions of ground state oxygen atoms with 1-pentene, 1-hexene, cis-2-pentene, and trans-2-pentene was investigated in the temperature range 200 to 370 K. In this range the temperature dependences of the rate constants can be represented by k = A′ Tⁿ exp(− E′_a/RT) with A′ = (1.0 ± 0.6) · 10⁻¹⁴ cm³ s⁻¹, n = 1.13 ± 0.02, E′_a = 0.54 ± 0.05 kJ mol⁻¹ for 1-pentene: A′ = (1.3 ± 1.2) · 10⁻¹⁴ cm³ s⁻¹, n = 1.04 ± 0.08, E′_a = 0.2 ± 0.4 kJ mol⁻¹ for 1-hexene; A′ = (0.6 ± 0.6) · 10⁻¹⁴ cm³ s⁻¹, n = 1.12 ± 0.05, E′_a = − 3.8 ± 0.8 kJ mol⁻¹ for cis-2-pentene; and A′ = (0.6 ± 0.8) · 10⁻¹⁴ cm³ s⁻¹, n = 1.14 ± 0.06, E′_a = − 4.3 ± 0.5 kJ mol⁻¹ for trans-2-pentene. The atoms were generated by the H₂-laser photolysis of NO and detected by time resolved chemiluminescence in the presence of NO. The concentrations of the O(³P) atoms were kept so low that secondary reactions with products are unimportant. © 1997 John Wiley & Sons, Inc.     

Synthesis and Characterization of Sulfonated Polyimides Containing Trifluoromethyl Groups as Proton Exchange Membranes

A novel sulfonated diamine, 4,4′‐bis(4‐amino‐3‐trifluoromethylphenoxy) biphenyl 3,3′‐disulfonic acid (F‐BAPBDS), was successfully synthesized by nucleophilic aromatic substitution of 4,4′‐dihydroxybiphenyl with 2‐chloro‐5‐nitrobenzotrifluoride, followed by reduction and sulfonation. A series of sulfonated polyimides of high molecular weight (SPI‐x, x represents the molar percentage of the sulfonated monomer) were prepared by copolymerization of 1,4,5,8‐naphathlenetetracarboxylic dianhydride (NTDA) with F‐BAPBDS and nonsulfonated diamine. Flexible and tough membranes of high mechanical strength were obtained by solution casting and the electrolyte properties of the polymers were intensively investigated. The copolymer membranes exhibited excellent oxidative stability due to the introducing of the CF₃ groups. The SPI membranes displayed desirable proton conductivity (0.52×10⁻¹–0.97×10⁻¹ S·cm⁻¹) and low methanol permeability (less than 2.8×10⁻⁷ cm²·s⁻¹). The highest proton conductivity (1.89×10⁻¹ S·cm⁻¹) was obtained for the SPI‐90 membrane at 80°C, with an IEC of 2.12 mequiv/g. This value is higher than that of Nafion 117 (1.7×10⁻¹ S·cm⁻¹). Furthermore, the hydrolytic stability of the obtained SPIs is better than the BDSA and ODADS based SPIs due to the hydrophobic CF₃ groups which protect the imide ring from being attacked by water molecules, in spite of its strong electron‐withdrawing behaviors.     

The thermodynamic characteristics of point defects and the mechanism of charge transfer in lanthanum cobaltite doped with strontium and nickel

The specific conductivity and thermal electromotive force (EMF) coefficient of lanthanum cobaltite doped with strontium and nickel La_0.9Sr_0.1Co_0.9Ni_0.1O_3−δ were measured over the temperature and pressure ranges 1023–1223 K and 10⁻⁶−1 atm. The oxide was found to exhibit metallic-type conductivity (800 Ω⁻¹ cm⁻¹ ≤ σ ≤ 1150 Ω⁻¹ cm⁻¹) and small positive thermal EMF coefficient values. A joint analysis of the thermodynamic characteristics of formation of point defects and external T and p _{O 2} parameter dependences of conductivity and thermal EMF showed that charge was transferred in the oxide by small-radius polarons according to the hopping mechanism. The role of polarons was played by electrons Me ^′_Co and holes Me ^•_Co localized on 3d transition metals. The isothermal dependences of the concentrations and mobilities of charge carriers on the degree of oxygen nonstoichiometry of the oxide studied were calculated.

     

Conformational analysis,barriers to internal rotation,ab initio calculations and vibrational assignment of fluoroacetone

The infrared (3500-20 cm⁻¹) and Raman (3200-10 cm⁻¹) spectra have been recorded for gaseous and solid fluoroacetone (1-fluoro-2-propanone), CH₂FC(O)CH₃. Additionally, the Raman spectrum of the liquid has been recorded and qualitative depolarization values have been obtained. These data have been interpreted on the basis that the molecule exists predominantly in the cis (fluorine atom oriented cis to the methyl group) conformation in the vapor but for the liquid a second conformer having a trans orientation (fluorine atom oriented trans to the methyl group) is present. From a study of the Raman spectrum of the liquid at variable temperatures the trans conformation has been determined to be more stable than the cis form by 416 ± 54 cm⁻¹ (1.19 ± 0.15 kcal mol⁻¹) and is the only conformation present in the spectrum of the annealed solid. The asymmetric torsional fundamental for the more stable cis conformer has been observed in the far infrared spectrum of the gas at 69.6 cm⁻¹ with six accompanying hot band transitions proceeding to lower frequency. The corresponding mode for the high energy trans conformer is extensively overlapped but is distinguishable at ∼65 cm⁻¹. From these data the asymmetric torsional potential function governing internal rotation about the CC bond has been determined and the potential coefficients are: V₁ = 675 ± 2, V₂ = 991 ± 5, V₃ = 74 ± 1 and V₄ = 54 ± 2 cm⁻¹. The cis to trans and trans to cis barriers are 1332 ± 5 and 731 ± 5 cm⁻¹, respectively, with an enthalpy difference of 601 ± 8 cm⁻¹ (1.72 ± 0.02 kcal mol⁻¹). From ab initio calculations at the 3-21G and 6-31G* basis set levels optimized geometries for both the cis and trans conformers have been obtained and the potential surface governing internal rotation of the asymmetric top determined. The observed vibrational frequencies with their assignments for both the cis and trans conformers are compared to those from the ab initio calculations. All of these results are compared to the corresponding quantities for some similar molecules.     

Superprotonic Conductivity of MOFs Confining Zwitterionic Sulfamic Acid as Proton Source and Conducting Medium

A few metal–organic frameworks (MOFs), which typically use strong acids as proton sources, display superprotonic conductivity (≈10⁻¹ S cm⁻¹); however, they are rare due to the instability of MOFs in highly acidic conditions. For the first time, we report superprotonic conductivity using a moderately acidic guest, zwitterionic sulfamic acid (HSA), which is encapsulated in MOF-808 and MIL-101. HSA acts not only as a proton source but also as a proton-conducting medium due to its extensive hydrogen bonding ability and zwitterion effect. A new sustained concentration gradient method results in higher HSA encapsulation compared to conventional methods, producing 10HSA@MOF-808-(bSA)₂ and 8HSA@MIL-101. These MOFs show impressive superprotonic conductivity of 2.47×10⁻¹ and 3.06×10⁻¹ S cm⁻¹, respectively, at 85 °C and 98 % relative humidity, and maintain stability for 7 days.     

Properties of polyphenylene films deposited electrochemically in an HF-benzene system

Free-standing polyphenylene films, prepared by the electrochemical oxidation of benzene in an HF-benzene, two-phase system, were investigated. From electron microscope pictures, x-ray diffraction patterns, and infrared (IR) spectra of polyphenylene films and commercial polyphenylene powder it is concluded that the films, which are largely para linked, contain in addition a substantial amount of meta and possibly ortho linkages and are amorphous in nature. Doping with AsF₅ increases the electrical conductivity of the otherwise insulating films to 10^?4?10^?2ohm^?1cm^?1; doped films are relatively stable in air. The lower conductivity of doped films with respect to reported values for chemically synthesized poly-p-phenylene appears to be the result of the amorphous nature of the films.     

Ion conductive poly(ethylene oxide-dimethyl siloxane) copolymers

A series of poly(ethylene oxide-dimethyl siloxane) copolymers, — [SiMe₂O(CH₂CH₂O)_n]_m — (n = 2, 3, 4, 5, 6.4, 8.7, 13.3), were synthesised by the reaction of polyethylene glycol with dimethyl dimethoxy/diethoxysilane. Corresponding ion-conductive polymers were prepared by complexing these copolymers with salts (sodium tetrafluoroborate or ammonium adipate). The highest conductivity of these systems at room temperature was 3 × 10⁻⁴ S cm⁻¹ and 6 × 10⁻⁵ S cm⁻¹, respectively. The glass transition temperature of these copolymers is reported and is seen to be dependent on the length of the ether units. The effects of siloxane content, salt concentration, and temperature on the conductivity are discussed. © 1996 John Wiley & Sons, Inc.     

Conductivity and thermogravimetric studies of HTi2NbO7 · 2H2O and CsTi2NbO7

A detailed study was performed of the interrelationships of the lattice parameters, ionic conductivity, and infrared spectrum of HTi₂NbO₇ · 2H₂O as a function of dehydration. We have shown that the oxide layers in this ion-exchange compound are interespaced with water layers 2-molecules thick, providing a rare example of a bilayer hydrate. Bulk proton transport occurs through these layers, with a conductivity of (8 ± 4) × 10^?6 ohm^?1cm^?1 at 20°C. Upon heating to 55°C, 0.5 H₂O per formula was gradually lost, but the conductivity was essentially retained. Upon further heating to 62°C another 0.5 H₂O was rapidly lost, resulting in a conductivity drop of a factor of 10. Further water was gradually lost until HTi₂NbO₇ was reached at 220°C. The X-ray evidence revealed no discrete, fixed-composition hydrate phases, indicating a single isostructural phase from HTi₂NbO₇ · 2H₂O to HTi₂NbO₇, with a single continuously variable interlayer spacing. The bulk conductivity of CsTi₂NbO₇ was less than 10^?8 ohm^?1cm^?1.     

Synthesis and characterization of epoxidized polybutadiene/polyaniline graft conducting copolymer

In this article the synthesis and characterization of an elastomeric conducting material, obtained by grafting polyaniline (EB) on commercial cis‐1,4‐polybutadiene (PB), are described. PB was first partially epoxidized in chloroform solution using meta‐chloroperbenzoic acid (MCPBA). The conducting polymer was then grafted to the activated polybutadiene (EPB) via the aminolysis reaction between the polyaniline NH₂ terminal groups and the oxirane rings. The material so obtained (EPBPAN) and the epoxidized intermediate product were characterized by ¹H NMR, ¹³C NMR, Fourier transform infrared, and ultraviolet–visible spectroscopy, thermal and mechanical analysis, and electrical conductivity measurements. The effect of the sample deformation on conductivity also was analyzed. The HCl doping of the EPBPAN film induced crosslinking reactions, generated by the acid cleavage of unreacted oxirane groups. The electrical conductivity of the doped material reached values of about 10^?5 Ω^?1 cm^?1. The key characteristics of our elastomeric conducting material are its simple synthesis, its starting as a commercial product, and the solubility of its undoped form in a common low‐boiling organic solvent like chloroform. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3082–3090, 2004     

Effect of Substrates on the Addition Polymerization of 1,4-Benzenedithiol to 1,4-Diethynylbenzene in the Solid State and the Electronic Properties of the Resulting Polymer

The effect of substrates on the addition polymerization of 1,4-benzenedithiol (BDT) to 1,4-diethynylbenzene (DEB) in the solid state and the electronic properties of the polymers obtained were studied. As the substrate polymer sheets, for instance, PET (poly (ethylene terephthalate)) sheet, ON-6 (oriented nylon-6) sheet and so on having surface free energies Γ_s from 27.4 to 55.0 erg/cm² were used. At the monomer sublimation temperature of 60°C, the S wt% (sulfur content) and the cis content of the polymers were not affected by the kind of polymer sheets. However, the molecular weights, M¯_n of the polymers polymerized on the polymer sheets were 13,000–30,000, and the values were several times higher than the molecular weight of the polymers polymerized on glass plate. On the other hand, at the sublimation temperature of 82°C, the cis content of the polymers apparently increased with decreasing d-value of the polymer sheets. On X-ray diffraction patterns of monomer mixtures sublimed onto polymer sheets, the diffraction intensities and the diffraction peak positions were concerned with the d-value of the polymer sheets. Using polymer sheets, the diffraction peak intensities of the monomer mixture at 7.73 and 7.58 Å decreased compared with those on glass plate. In contrast, the peak at 3.65 Å, which is a negligibly small peak on glass plate, obviously increased. However, as the d-value of the polymer sheets (PET 3.45 Å; OPP (oriented polypropylene) 5.2 Å) increased, the diffraction peak intensities at 7.73 Å and 7.58 Å gradually increased and the diffraction peak intensity at 3.65 Å gradually decreased. The parallel electrical conductivities (σ_||) toward the layered structural polymer on PET, ON-6 and glass plate under air atmosphere were 10⁻⁷, 10⁻⁹ and 10⁻¹¹ S/cm, respectively. Under a reduced pressure of 10⁻³ mmHg, the σ_|| values of each polymer lowered by one or two orders of magnitude. On the other hand, the σ_|| values of the nonlayered structural polymers under air atmosphere were about 10⁻¹¹–10⁻¹² S/cm and were independent of the substrates. Even under a reduced pressure of 10⁻³ mmHg, the σ_|| values hardly changed and remained at 10⁻¹¹–10⁻¹² S/cm. The vertical electrical conductivities (σ_⟂) of the layered structural polymers on conductive PET sheet coated by indium tin oxide or NESA glass plates were independent of the substrates and were 10⁻¹⁴ S/cm under air atmosphere. The σ_⟂ values of the nonlayered structural polymers also exhibited the same values. The reversible change of the amount of the layered structural polymer on PET sheet was also caused by irradiation of the photo-light which is the effective wavelength for the phase transition of the polymers mounted on glass plate. The σ_|| value of the layered structural polymer on ON-6 sheet reversibly changed with the amount of the layer structure controlled by the photo-light, that is, the σ_|| increased up to about one order of magnitude by the photo-light at 545.6 nm. On the other hand, the _|| decreased to about one order of magnitude by the photo-light at 539.6 nm. Anisotropic conductivity with respect to σ_|| and σ_⟂, and oxygen doping mechanisms were discussed in relation to the layer structure of polymers. © 1997 John Wiley & Sons, Ltd.     

Kinetic study of gas-phase reactions of pinonaldehyde and structurally related compounds

Rate constants for the reactions of OH, NO₃, and O₃ with pinonaldehyde and the structurally related compounds 3-methylbutanal, 3-methylbutan-2-one, cyclobutyl-methylketone, and 2,2,3-trimethyl-cyclobutyl-1-ethanone have been measured at 300±5 K using on-line Fourier transform infrared spectroscopy. The rate constants obtained for the reactions with pinonaldehyde were: k_OH=(9.1±1.8)×10⁻¹¹ cm³ molecule⁻¹ s⁻¹, k_NO3=(5.4±1.8)×10⁻¹⁴ cm³ molecule⁻¹ s⁻¹, and k_O3=(8.9±1.4)×10⁻²⁰ cm³ molecule⁻¹ s⁻¹. The results obtained indicate a chemical lifetime of pinonaldehyde in the troposphere of about two hours under typical daytime conditions, [OH]=1.6×10⁶ molecule cm⁻³. © 1997 John Wiley & Sons, Inc. Int J Chem Kinet 29: 527–533, 1997.     

ELECTRICAL PROPERTIES OF M(S2C2(CN)2)2 1-(M=Ni,Pt) COMPLEXES

Abstract

Single crystal conductivity studies over a temperature range of 200°K to 400°K have been carried out on various M(S₂C₂(CN)₂)₂ ^1-(M=Ni,Pt) salts. A room temperature conductivity of ～ 10^?10ohm^?1 cm^?1 and an E_a?0.5 eV was observed for each of these systems. These results are correlated with the magnetic, electronic, and crystallographic properties. The semiconducting behavior of these systems is related to the electronic structure of the molecular anion.     

Single-ion and salt conductor polymer electrolytes based on poly(4-vinylpyridine) quaternized with poly(ethylene oxide) side chains

A new type of single-ion conductor with fixed cation was synthesized by spontaneous anionic polymerization of 4-vinylpyridine in the presence of short polyethylene oxide ( PEO ) chains as alkylating agents. These comblike polymers have low T_gs and are amorphous with the shorter PEO s. Their conductivities are unaffected by the nature of the anion ( Br ⁻, ClO ₄⁻, and tosylate) and are controlled by the free volume and the mobility of the pendant cation. By comparison of the results at constant free volume, it is shown that the charge density decreases with the increasing length of pendant PEO demonstrating that PEO acts only as a plasticizing agent. Best conductivity results (σ = 10⁻⁵ S cm⁻¹ at 60°C) are obtained with PEO side chains of molecular weight 350. With this sample, the conductivity in the presence of various amounts of added salt (LiTFSI) was studied. A best value of 10⁻⁴ S cm⁻¹ at 60°C is obtained with a molar ratio EO/Li of 10. It is shown that, over the range of examined concentrations (0.2–1.3 mol Li kg⁻¹), the reduced conductivity σ_r/c increases linearly with increasing salt concentration showing that the ion mobility increases continuously. Such behavior is quite unusual since in this concentration range a maximum is generally observed with PEO systems. To interpret this result and by analogy with the behavior of this type of polymer in solution, it is proposed that the conformation of these polymers in the solid state is segregated with the P4VP skeleton more or less confined inside the dense coils surrounded by the PEO side chains. Under the influence of the increasing salt concentration, this microphase separation vanishes progressively: The LiTFSI salt exchanges with the tosylate anions and acts as a miscibility improver agent. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 2719–2728, 1997     

A Carbocationic Triarylmethane-Based Porous Covalent Organic Network

A thermally stable carbocationic covalent organic network (CON), named RIO-70 was prepared from pararosaniline hydrochloride, an inexpensive dye, and triformylphloroglucinol in solvothermal conditions. This nanoporous organic material has shown a specific surface area of 990 m² g⁻¹ and pore size of 10.3 Å. The material has CO₂ uptake of 2.14 mmol g⁻¹ (0.5 bar), 2.7 mmol g⁻¹ (1 bar), and 6.8 mmol g⁻¹ (20 bar), the latter corresponding to 3 CO₂ molecules adsorbed per pore per sheet. It is shown to be a semiconductor, with electrical conductivity (σ) of 3.17×10⁻⁷ S cm⁻¹, which increases to 5.26×10⁻⁴ S cm⁻¹ upon exposure to I₂ vapor. DFT calculations using periodic conditions support the findings.     

A new class of proton-conducting ionic plastic crystals based on organic cations and dihydrogen phosphate

Choline dihydrogen phosphate ([N_1.1.1.2OH]DHP) and 1-butyl-3-methylimidazolium dihydrogen phosphate ([C₄mim]DHP) were synthesized as a new class of proton-conducting ionic plastic crystals. Both [N_1.1.1.2OH]DHP and [C₄mim]DHP showed solid–solid phase transition(s) and showed a final entropy of fusion lower than 20 J K⁻¹ mol⁻¹ which is consistent with Timmerman’s criterion for molecular plastic crystals. The ionic conductivity of [N_1.1.1.2OH]DHP was in the range of 10⁻⁶ S cm⁻¹–10⁻³ S cm⁻¹ in the plastic crystalline phase. On the other hand, the ionic conductivity of [C₄mim]DHP showed about 10⁻⁵ S cm⁻¹ in the plastic crystalline phase. [N_1.1.1.2OH]DHP showed one order of magnitude higher ionic conductivity than [C₄mim]DHP in the temperature range where the plastic phase is stable.     

Gold(III) Complexes of Asymmetrically Aryl‐Substituted 1,2‐Dithiolene Ligands Featuring Potential‐Controlled Spectroscopic Properties: An Insight into the Electronic Properties of bis(Pyren‐1‐yl‐ethylene‐1,2‐dithiolato)Gold(III)

The electrochemical, UV/Vis–NIR absorption, and emission‐spectroscopic features of (TBA⁺)( 1 ⁻) and the corresponding neutral complex 1 were investigated (TBA⁺=tetrabutylammonium; 1 ⁻=[Au^III(Pyr,H‐edt)₂]⁻; Pyr,H‐edt²⁻=pyren‐1‐yl‐ethylene‐1,2‐dithiolato). The intense electrochromic NIR absorption (λ_max=1432 nm; ε=13000 M ⁻¹ cm⁻¹ in CH₂Cl₂) and the potential‐controlled visible emission in the range 400–500 nm, the energy of which depends on the charge of the complex, were interpreted on the grounds of time‐dependent DFT calculations carried out on the cis and trans isomers of 1 , 1 ⁻, and 1 ²⁻. In addition, to evaluate the nonlinear optical properties of 1 ^x− (x=0, 1), first static hyperpolarizability values β_tot were calculated (β_tot=78×10⁻³⁰ and 212×10⁻³⁰ esu for the cis isomer of 1 ⁻ and 1 , respectively) and compared to those of differently substituted [Au(Ar,H‐edt)₂]^x− gold dithiolenes [Ar=naphth‐2‐yl ( 2 ), phenyl ( 3 ); x=0, 1].