Supramolecular Assembly of a 2D Binary Network of Pentacene and Phthalocyanine on Cu(100)

A crystalline nanoporous molecular network was tailored by supramolecular assembly of pentacene and F₁₆CuPc on Cu(100). The structure and self‐assembly mechanisms of the pure and binary layers were analyzed by STM. F₁₆CuPc films and mixed layers of pentacene/F₁₆CuPc in a ratio of 2:1 show two enantiomorphic chiral domains with high structural order in contrast to pentacene which exhibits no long‐range order in pure films. A model of the epitaxial relationship on Cu(100) is given, which suggests C? F???H bonding as a possible driving force for the bimolecular self‐assembly in addition to the still strong interaction between the substrate and the organic bilayer.     

Interactions of copper tetra-tert-butylphthalocyanine with nitrogen- and sulfur-containing compounds in solutions

Interactions of ammonia, aliphatic amines, hydrogen sulfide, and sulfur dioxide with copper tetra-tert-butylphthalocyanine (CuPc) in squalane were studied by spectrophotometry and gas liquid chromatography in the CuPc concentration range of 1·10^–3—5·10^–2 mol L^–1. The sorption properties of the CuPc—squalane stationary liquid phases (SLPs) are governed by the physicochemical nature of the CuPc nanoaggregates in solution. The -type nanoaggregates exhibit particularly high activity to hydrogen sulfide; the activities to primary and secondary amines are also high.     

Reactions of Nitro and Halonitro Derivatives of Aluminum(III) and Copper(II) Phthalocyanines with Concentrated Sulfuric Acid

Transformations of the complexes CuPc(4-NO₂)₄, CuPc(4-Br)₄(5-NO₂)₄, (OH)AlRs(4-NO₂)₄, and (OH)AlPc(4-Cl)₄(5-NO₂)₄ in concentrated sulfuric acid were studied by spectrophotometry. One protonated form of CuPc(4-Br)₄(5-NO₂)₄ and (OH)AlPc(4-NO₂)₄ and two protonated forms of CuPc(4-NO₂)₄ and (OH)AlPc(4-Cl)₄(5-NO₂)₄ were detected experimentally and also by ZINDO1 calculations. Step protonation constants of CuPc(4-NO₂)₄ and (OH)AlPc(4-Cl)₄(5-NO₂)₄ were determined by quantum-chemical calculations and acid-base titration; these complexes can be regarded as weak bases with respect to H₂SO₄. The kinetics of dissociation of the complexes at the MÄN bonds were studied. The rate of dissociation of the Cu(II) complexes and (OH)AlPc(4-NO₂)₄ is proportional to [MPc(R) _n ] and [H₃O⁺]². The rate of dissociation of (OH)AlPc(4-Cl)₄(5-NO₂)₄ showed a weak extremal dependence on the composition of the medium, which was explained by change of its structure in 17.0 M H₂SO₄. The electronic effect of substituents on the reaction center was considered with account taken of a complex mechanism of activation and fine details of the molecular structure of macrocyclic complexes.     

Synthesis and 1.1 μm near-infrared electrophosphorescence properties of a phenoxy-substituents copper phthalocyanine

A novel copper phthalocyanine bearing phenoxy-substituents was prepared and characterized by MS and Elemental analysis. Its UV/Vis absorption and photoluminescence (PL) spectra were investigated. Organic light-emitting devices (OLEDs) were demonstrated by employing this copper phthalocyanine doped into 4, 4′-N,N′-dicarbazole-biphenyl (CBP). Room-temperature electrophosphorescence was observed at about 1.1 μm due to transitions from the first excited triplet state to the singlet ground state (T ₁–S₀) of this CuPc. The intensity of NIR emission at lower doping concentrations (about 10 wt %) was extremely high compared with devices doped with fluorescent dyes. The results indicated that direct charge trapping appears to be the dominant mechanism. The article is published in the original.     

Copper Phthalocyanine Layer as an Organic Semiconductor Sensor of NO2 in Air

Abstract

The applicability of copper phthalocyanine (CuPc) as an organic semiconductor gas sensor for the detection of high concentrations of NO₂ in air is the aim of this study. Thin films of CuPc were deposited by sublimation. Measurements were carried out to determine the effect of NO₂ on the conductivity of a CuPc film. A detection method for NO₂ in air is proposed.     

Microwave-assisted synthesis and reverse saturable absorption of phthalocyanines and porphyrins

Soluble phthalocyanines, including tetrakis(2,9,16,23-cumylphenoxy) copper phthalocyanines (CuPc(β-CP)₄), tetrakis(1,8,15,22-cumylphenoxy) copper phthalocyanines (CuPc(α-CP)₄) as well as tetrakis(2,9,16,23-tert-butyl) copper phthalocyanines (CuPc(β-t-butyl)₄), and porphyrins (5,10,15,20-tetrakis(4-tert-butylphenyl)porphyrins; M(TBP), M=H₂, Zn, Cu, Mg, InCl, AlCl) have been quickly synthesized by microwave irradiation. Furthermore, their reverse saturable absorption have also been investigated by dissolving them in solvent or incorporating them in polymer-silica hybrid material with a sol-gel process with polyvinyl butyral and tetraethyl orthosilicate as precursors. A new method for the preparation process of phthalocyanines and porphyrins in the solids has been successfully used.     

Colloidal Synthesis and Charge‐Carrier Dynamics of Cs2AgSb1−yBiyX6 (X: Br,Cl; 0 ≤y ≤1) Double Perovskite Nanocrystals

A series of lead‐free double perovskite nanocrystals (NCs) Cs₂AgSb_1?yBi_yX₆ (X: Br, Cl; 0≤y≤1) is synthesized. In particular, the Cs₂AgSbBr₆ NCs is a new double perovskite material that has not been reported for the bulk form. Mixed Ag–Sb/Bi NCs exhibit enhanced stability in colloidal solution compared to Ag–Bi or Ag–Sb NCs. Femtosecond transient absorption studies indicate the presence of two prominent fast trapping processes in the charge‐carrier relaxation. The two fast trapping processes are dominated by intrinsic self‐trapping (ca. 1–2 ps) arising from giant exciton–phonon coupling and surface‐defect trapping (ca. 50–100 ps). Slow hot‐carrier relaxation is observed at high pump fluence, and the possible mechanisms for the slow hot‐carrier relaxation are also discussed.     

Colloidal Synthesis and Charge‐Carrier Dynamics of Cs2AgSb1−yBiyX6 (X: Br,Cl; 0 ≤y ≤1) Double Perovskite Nanocrystals

A series of lead‐free double perovskite nanocrystals (NCs) Cs₂AgSb_1?yBi_yX₆ (X: Br, Cl; 0≤y≤1) is synthesized. In particular, the Cs₂AgSbBr₆ NCs is a new double perovskite material that has not been reported for the bulk form. Mixed Ag–Sb/Bi NCs exhibit enhanced stability in colloidal solution compared to Ag–Bi or Ag–Sb NCs. Femtosecond transient absorption studies indicate the presence of two prominent fast trapping processes in the charge‐carrier relaxation. The two fast trapping processes are dominated by intrinsic self‐trapping (ca. 1–2 ps) arising from giant exciton–phonon coupling and surface‐defect trapping (ca. 50–100 ps). Slow hot‐carrier relaxation is observed at high pump fluence, and the possible mechanisms for the slow hot‐carrier relaxation are also discussed.     

Electrocatalysts Derived from Copper Complexes Transform CO into C2+ Products Effectively in a Flow Cell

Electrochemical reactors that electrolytically convert CO₂ into higher-value chemicals and fuels often pass a concentrated hydroxide electrolyte across the cathode. This strongly alkaline medium converts the majority of CO₂ into unreactive HCO₃⁻ and CO₃²⁻ byproducts rather than into CO₂ reduction reaction (CO2RR) products. The electrolysis of CO (instead of CO₂) does not suffer from this undesirable reaction chemistry because CO does not react with OH⁻. Moreover, CO can be more readily reduced into products containing two or more carbon atoms (i. e., C₂₊ products) compared to CO₂. We demonstrate here that an electrocatalyst layer derived from copper phthalocyanine ( CuPc ) mediates this conversion effectively in a flow cell. This catalyst achieved a 25 % higher selectivity for acetate formation at 200 mA/cm² than a known state-of-art oxide-derived Cu catalyst tested in the same flow cell. A gas diffusion electrode coated with CuPc electrolyzed CO into C₂₊ products at high rates of product formation (i. e., current densities ≥200 mA/cm²), and at high faradaic efficiencies for C₂₊ production (FE_C2+; >70 % at 200 mA/cm²). While operando Raman spectroscopy did not reveal evidence of structural changes to the copper molecular complex, X-ray photoelectron spectroscopy suggests that the catalyst undergoes conversion to a metallic copper species during catalysis. Notwithstanding, the ligand environment about the metal still impacts catalysis, which we demonstrated through the study of a homologous CuPc bearing ethoxy substituents. These findings reveal new strategies for using metal complexes for the formation of carbon-neutral chemicals and fuels at industrially relevant conditions.     

The improved efficiency of low molecular weight organic solar cells doped with a Cu(I) triplet material

We developed a method to improve the performance of the copper phthalocyanine (CuPc)/fullerene (C₆₀) organic solar cells (OSCs) by doping CuPc with a long triplet lifetime material. By doping [Cu(bis[2-(diphenylphosphino)phenyl]ether)(benzo[i]dipyrido[3,2-a:2′,3′-c]phenazine)]BF₄ (CuDB) into CuPc, the enhanced short-circuit current density (J_SC) of 6.213 mA/cm², open-circuit voltage (V_OC) of 0.39 V and a peak power conversion efficiency (PCE) of 0.92% compared to 0.79% of the standard CuPc/C₆₀ OSCs are achieved under 1 sun AM 1.5 G illumination at an intensity of 100 mW/cm². The performance improvement is mainly attributed to the long triplet lifetime of CuDB (τ = 70.05 μs) which leads to more effective exciton dissociation.     

In-situ Synthesis of Copper Phthalocyanine in Silica Xerogel Matrix

Using a newly developed in-situ syntheses technique during sol-gel process, copper phthalocyanine (CuPc) is synthesized in-situ in silica xerogel matrix homogeneously. It has been confirmed by UV-Vis and IR spectroscopies that the copper ions which existed in the form of complex-ions [Cu(H₂O)₄]²⁺ and [CuCl₄]^2– in the stages of sol and wet gel were destroyed in the heat treatment process, meanwhile the copper phthalocyanine molecules were synthesized in-situ gradually during the wet gel to xerogel transition. The dimerization phenomenon of CuPc in the composite is suppressed greatly because the in-situ synthesized CuPc molecules were well isolated in the micro-pores of the xerogel matrix. The doping concentration of Copper phthalocyanine in sol-gel derived matrix can be enhanced also by this in-situ synthesis method.     

The Very low-pressure pyrolysis of 2-phenylethylamine. The enthalpy of formation of the aminomethyl radical

The thermal unimolecular decomposition of 2-phenylethylamine (PhCH₂CH₂NH₂) into benzyl and aminomethyl radicals has been studied under very-low-pressure conditions, and the enthalpy of formation of the aminomethyl radicals, ΔH°_{f, 298K} (H₂NCH₂·) = 37.0 ± 2.0 kcal/mol, has been derived from the kinetic data. This result leads to a value for the C—H bond dissociation energy in methylamine, BDE(H₂NCH₂—H) = 94.6 ± 2.0 kcal/mol, which is about 3.4 kcal/mol lower than in C₂H₆ (98 kcal/mol), indicating a sizable stabilization in α-aminoalkyl radicals.     

A computational investigation on the photochemistry of the popular spin-trap agent N-tert-butyl-α-phenylnitrone (PBN) and thermal isomerization pathways of its photoproduct oxaziridine

Computational investigation on the low-lying photo-excited states of N-tert-butyl-α-phenylnitrone (PBN), a well-known spin-trap agent, has revealed its photo-product (oxaziridine) formation channel. The S₀-S₂ vertical excitation in PBN is subsequently followed by a non-radiative decay pathway through S₂/S₁ and S₀/S₁ conical intersections (CIs) with CNO-kinked structures, situated around 23 kcal/mol and 45 kcal/mol below the vertically excited S₂ state, respectively. The reverse photo-process of PBN formation involves photo-excitation of oxaziridine to its S₂ and S₃ photo-excited states. The forward photo-isomerization leads to the trans-oxaziridine with a backside CNO kink (trans-OX_B) while the reverse path studied by us, connects its front-side CNO-kinked analogue (trans-OX_F) with the PBN. Our search for the reverse thermal reaction paths from these two oxazirdines has led to their corresponding transition states, one at 35 kcal/mol and the other at 27 kcal/mol above trans-OX_F and trans-OX_B geometries, respectively. They lead to two different isomers (E and Z) of PBN which supports the reported nature of products from the trans-oxaziridine in this thermal reaction. The inversion path of the chiral nitrogen atom of this N-tert-butyl-oxaziridine (barrier 21 kcal/mol) has also been tracked. This reaction path has been compared with that of the N-methyl (barrier 30 kcal/mol) and N-acyl (barrier 10.5 kcal/mol) oxaziridine analogues.     

The very low-pressure pyrolysis of phenyl methyl sulfide and benzyl methyl sulfide. The enthalpy of formation of the methylthio and phenylthio radicals

The kinetics and mechanisms of the unimolecular decompositions of phenyl methyl sulfide (PhSCH₃) and benzyl methyl sulfide (PhCH₂SCH₃) have been studied at very low pressures (VLPP). Both reactions essentially proceed by simple carbon-sulfur bond fission into the stabilized phenylthio (PhS·) and benzyl (PhCH₂·) radicals, respectively. The bond dissociation energies BDE(PhS-CH₃) = 67.5 ± 2.0 kcal/mol and BDE(PhCH₂-SCH₃) = 59.4 ± 2 kcal/mol, and the enthalpies of formation of the phenylthio and methylthio radicals ΔH° _,298K(PhS·, g) = 56.8 ± 2.0 kcal/mol and ΔH°_{f, 298K}(CH₃S·, g) = 34.2 ± 2.0 kcal/mol have been derived from the kinetic data, and the results are compared with earlier work on the same systems. The present values reveal that the stabilization energy of the phenylthio radical (9.6 kcal/mol) is considerably smaller than that observed for the related benzyl (13.2 kcal/mol) and phenoxy (17.5 kcal/mol) radicals.     

Synthesis and photoconductivity study of phthalocyanine polymers. II. PVK-co-CuPc (COOH)3

Cu-phthalocyanine diimide (Cu-diPc) was synthesized from a mixture of phthalic anhydride and pyromellitic dianhydride. By the hydrolysis of Cu-diPc, Cu-4,4′,5,5′-tetracarboxy-phthalocyanine (Cu-taPc) was obtained. A novel polymer of polyvinylcarbazole-bonded CuPc(COOH)₃ ( I ) was synthesized by the Friedel–Crafts reaction of polyvinylcarbazole (PVK) with Cu-phthalocyanine-4,4′,5,5′-tetraacid chloride. Polymer ( I ) contains ca. 5 mol % CuPc(COOH)₃ rings, which are covalently bonded to PVK. Polymer ( I ) shows good photoconductivity, which is much better than that of the corresponding phthalocyanine monomers. The factors that influence the photoconductivity, such as the thickness of IFL, and the types and proportion of CTM, were also studied. © 1993 John Wiley & Sons, Inc.     

DNA-Triggered Enhancement of Singlet Oxygen Production by Pyridinium Alkynylanthracenes

There is an ongoing interest in ¹O₂ sensitizers, whose activity is selectively controlled by their interaction with DNA. To this end, we synthesized three isomeric pyridinium alkynylanthracenes 2 o – p and a water-soluble trapping reagent for ¹O₂. In water and in the absence of DNA, these dyes show a poor efficiency to sensitize the photooxygenation of the trapping reagent as they decompose due to electron transfer processes. In contrast, in the presence of DNA ¹O₂ is generated from the excited DNA-bound ligand. The interactions of 2 o – p with DNA were investigated by thermal DNA melting studies, UV/vis and fluorescence spectroscopy, and linear and circular dichroism spectroscopy. Our studies revealed an intercalative binding with an orientation of the long pyridyl-alkynyl axis parallel to the main axis of the DNA base pairs. In the presence of poly(dA : dT), all three isomers show an enhanced formation of singlet oxygen, as indicated by the reaction of the latter with the trapping reagent. With green light irradiation of isomer 2 o in poly(dA : dT), the conversion rate of the trapping reagent is enhanced by a factor >10. The formation of ¹O₂ was confirmed by control experiments under anaerobic conditions, in deuterated solvents, or by addition of ¹O₂ quenchers. When bound to poly(dG : dC), the opposite effect was observed only for isomers 2 o and 2 m , namely the trapping reagent reacted significantly slower. Overall, we showed that pyridinium alkynylanthracenes are very useful intercalators, that exhibit an enhanced photochemical ¹O₂ generation in the DNA-bound state.     

NaBO2-NaCl-Na2CO3, NaBO2- Na2CO3-NaMoO4, NaBO2- Na2CO3-NaWO4, and NaBO2-NaCl-Na2WO4 ternary systems

The phase diagrams of the NaBO₂-NaCl-Na₂CO₃, NaBO₂-Na₂CO₃-Na₂MoO₄, NaBO₂- Na₂CO₃-Na₂WO₄, and NaBO₂-NaCl-Na₂WO₄ ternary systems were studied by a calculation-experimental method and differential thermal analysis. The coordinates of ternary eutectics were determined: E ₁: 612°C, 16 mol % NaBO₂, 42 mol % NaCl, and 42 mol % Na₂CO₃; E ₂: 568°C, 12 mol % NaBO₂, 28 mol % Na₂CO₃, and 60 mol % Na₂MoO₄; E ₃: 575°C, 12 mol % NaBO₂, 32 mol % Na₂CO₃, and 56 mol % Na₂WO₄; E ₄: 628°C, 8 mol % NaBO₂, 20 mol % NaCl, and 72 mol % Na₂WO₄; and E ₅: 655°C, 9 mol % NaBO₂, 53 mol % NaCl, and 38 mol % Na₂WO₄.     

Enhanced Four-Electron Selective Oxygen Reduction Reaction at Carbon-Nanotube-Supported Sulfonic-Acid-Functionalized Copper Phthalocyanine

In the present work, the oxygen reduction reaction (ORR) is explored in an acidic medium with two different catalytic supports (multi-walled carbon nanotubes (MWCNTs) and nitrogen-doped multi-walled carbon nanotubes (NMWCNTs)) and two different catalysts (copper phthalocyanine (CuPc) and sulfonic acid functionalized CuPc (CuPc-SO₃⁻)). The composite, NMWCNTs-CuPc-SO₃⁻ exhibits high ORR activity (assessed based on the onset potential (0.57 V vs. reversible hydrogen electrode) and Tafel slope) in comparison to the other composites. Rotating ring disc electrode (RRDE) studies demonstrate a highly selective four-electron ORR (less than 2.5 % H₂O₂ formation) at the NMWCNTs-CuPc-SO₃⁻. The synergistic effect of the catalyst support (NMWCNTs) and sulfonic acid functionalization of the catalyst (in CuPc-SO₃⁻) increase the efficiency and selectivity of the ORR at the NMWCNTs-CuPc-SO₃⁻. The catalyst activity of NMWCNTs-CuPc-SO₃⁻ has been compared with many reported materials and found to be better than several catalysts. NMWCNTs-CuPc-SO₃⁻ shows high tolerance for methanol and very small deviation in the onset potential (10 mV) between the linear sweep voltammetry responses recorded before and after 3000 cyclic voltammetry cycles, demonstrating exceptional durability. The high durability is attributed to the stabilization of CuPc-SO₃⁻ by the additional coordination with nitrogen (Cu-N_x) present on the surface of NMWCNTs.     

Evolution of ordered films of copper phthalocyanine according to EPR data

The procedure for calculating the orientation distribution of molecules using the angular dependence of EPR spectra was employed to study copper(II) phthalocyanine (CuPc) films varying in thickness and obtained by depositing the molecular complex on flat quartz plates. At the first stage of deposition, a layer of the α-CuPc phase with preferable orientation of molecular stacks along the plate surface is formed. At the second stage, a layer with an orthogonal arrangement of molecular stacks is condensed over the first layer. The interaction with NO₂ forms CuPc binuclear associates. Analysis of the EPR spectra made it possible to determine the symmetry of the structure and the distance between the paramagnetic Cu²⁺ ions; the structure of the associates has been proposed. The orientation distribution of CuPc dimers in the film depends both on the initial ordering in the film and on processing conditions. Strong disordering of molecular stacks in ordered films during the α-CuPc to α-CuPc phase transition has been found.     

LCGTO-LSD calculations for CH2

LCGTO-LSD calculations for ground (³B₁) and excited (¹A₁) states of methylene, CH₂, have been performed. Various exchange-correlation potentials and a variety of basis sets (including f functions) have been used. For both states the LSD optimized geometry agrees well with both experimental and the most advanced ab initio results. The correct ground state is found, and the ¹A₁-³B₁ energy separation was found to be ～ 15 kcal/mol, using the “best” local exchange-correlation potential (VWN ), the experimental value being ～ 9 kcal/mol. This result compares favorably with the Hartree-Fock limit separation of 25 kcal/mol. The Kohn-Sham exchange potential leads to a gap of ～26 kcal/mol.