Substituted Copper Phthalocyanine Research Articles

Catalytic Oxidation of Benzyl Alcohol to Efficiently Synthesize Amide by (−CF3) Substituted Copper Phthalocyanine Based Composite Catalyst

AbstractUsing a type of tetra‐substituted metal phthalocyanine carbon nanotubes composite material [4 a (OPh‐p‐CF3)CuPc]‐MWCNTs as a catalyst, a method to synthesize benzamides through the oxidative amidation of benzyl alcohol was developed. Synthesize copper phthalocyanine by simple DBU liquid phase catalytic method, and then load phthalocyanine on carbon nanotubes by ultrasound to form four‐substituted metal phthalocyanine carbon nanotubes composite material [4 a (OPh‐p‐CF3)CuPc]‐MWCNTs. The composite materials were detected by ultraviolet visible spectroscopy (UV‐Vis), Fourier transforms infrared spectroscopy (FT‐IR), X‐ray diffraction spectroscopy (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). To achieve high‐efficiency and optional catalyze, studied solvent type, oxidant type and dosage, catalyst dosage, time and temperature. In the screening experiment, [4 a (OPh‐p‐CF3)CuPc]‐MWCNTs composite material has high catalytic ability in the oxidation of benzyl alcohol. At the greatest of times, the highest conversion ratio of benzyl alcohol (100 %), selectivity of benzamide (89 %) was obtained. The oxidant was TBHP and the amount was 3 mL, 60 °C for 24 h in DMF. Different kinds of amides were set up by various substituted benzyl alcohols, and good results were obtained.

Room temperature highly sensitive chlorine sensor based on reduced graphene oxide anchored with substituted copper phthalocyanine

The development of low cost, efficient and reversible chemiresistive sensors is one of the future challenges for the detection of harmful and toxic gases. In this direction, the effect of anchoring of hexadecafluorinated copper phthalocyanine (F16CuPc) molecules on to the reduced graphene oxide (rGO) sheets has been investigated for the first time, to develop a room-temperature chemiresistive sensor that can efficiently detect chlorine (Cl2) even down to few parts per billion (ppb) level. The rGO/F16CuPc hybrid materials characterized by X-ray photoelectron, Raman, Fourier transform infrared and ultraviolet-visible spectroscopy techniques indicated the presence of a strong synergetic interaction between the F16CuPc molecule and rGO sheet. Besides, scanning electron microscopic studies revealed that F16CuPc molecules assembled to form nano-flower type structures on rGO sheets. Under optimal conditions, the as-fabricated sensor exhibited improved response/recovery characteristics in comparison to its unsubstituted rGO/CuPc counterpart. The significant improvement in gas sensing characteristics has been independently verified by electrochemical impedance spectroscopy technique.

Copper (II) phthalocyanines: Electrode modification and sensing studies

Metal phthalocyanine complexes have been used as electro catalysts in various reactions. Chemically inert and thermally stable Para chloro phenyl [1,3,4] oxadiazole substituted copper phthalocyanine was used for the determination of dopamine and ascorbic acid. Experiments revealed that the compound possesses strong electro catalytic activity towards the oxidation of dopamine and ascorbic acid. The modified carbon paste electrode (MCPE) has talented features such as simplicity of electrode preparation, high stability and distinct advantage of simple polishing. Also there was no leaching or discharge of electrode because of insoluble nature of phthalocyanine in aqueous solution and hence a single electrode surface can be used for multiple analytical determinations.

Electron Charge Transport in Non-Peripherally Substituted Copper Phthalocyanine

Bottom-gate, bottom-contact organic thin film transistors (OTFTs) were fabricated using solvent soluble copper-1,4,8,11,15,18,22,25-octakis(hexyl)phthalocyanine as the active semiconductor layer. The compound was deposited as 70 nm thick spin-coated films onto gold source-drain electrodes supported on octadecyltrichlorosilane treated 250 nm thick SiO2 gate insulator. The analysis of experimental results showed the n-type field effect behaviour. Devices annealed at 100 oC under vacuum were found to exhibit the field-effect mobility of 0.0989 cm2 V−1 s−1, with an on/off current modulation ratio of ∼106, a reduced threshold voltage of 0.7 V and a sub-threshold swing of 2.12 V decade−1. The variations in surface morphology of the devices are found reflected considerably in the electrical measurements. The device contact resistance was found to be decreased as the gate bias increased and also with the annealing.

Effect of asymmetrical peripheral substitution of sulfonic acid group on the geometric and electronic structures and vibrations of copper phthalocyanine studied by computational and experimental techniques

The optimized geometry and vibrational frequencies of an organic compound copper phthalocyanine tetrasulfonic acid tetra sodium salt (CuPcTS) have been investigated using density functional theory. We have also optimized the structures of copper phthalocyanine (CuPc) and its substituted complex and simulated their vibrational spectra to study the substitution effects of sulfonic acid group at the peripheral sites of copper phthalocyanine. Experimentally, vibrational frequencies of these molecules have been studied using infrared absorption, Raman spectroscopic techniques. It has been found that the vibrational frequencies obtained from the theoretical studies generally agree with the experiment. Most of the bands show red shift in CuPcTS due to decrease of stretching force constant of CC and reduction in the contribution from in-plane CH bending vibrations. New bands have been observed due to SO vibrations. Degeneracy of IR bands is removed because of change of symmetry from D4h in CuPc to C1 in substituted CuPc. Effect of substitution on the structural parameters and mode compositions of the vibrational bands have also been studied. The electronic absorption spectra of the substituted copper phthalocyanine in different solvents have been studied using UV–Vis spectroscopy. It has been found that the substituted copper phthalocyanine shows aggregation effect in water because of greater extent of hydrogen bonding. The direct optical band gap energy and refractive index of CuPcTS have also been calculated in the different solvents. We have also plotted the IV characteristic for both the molecules and it has been found that electrical and photoconductivity of CuPcTS is more as compared to CuPc. The intermolecular charge transfer interactions have been studied by HOMO-LUMO and natural bonding orbital (NBO) analysis. The values of first order hyperpolaizability for both the molecules indicate that substituted copper phthalocyanine acquires excellent non-linear optical (NLO) properties. The interaction sites of the both the molecules have been studied by the molecular electrostatic potential (MEP) and solvent accessible surface area (SASA) analysis.

Electrochemical pesticide sensor based on anthraquinone substituted copper phthalocyanine

In this study, a biomimetic selective pesticide electrochemical sensor based on copper phthalocyanine-anthraquinone hybrid (CuPc-AQ) was studied. Electrochemical activities based on Pc ring and anthraquinone substituent of the CuPc-AQ make it valuable material for electrochemical sensor studies in detecting of pesticides. Thin film of CuPc-AQ on ITO electrode (ITO/CuPc-AQ) was exposed to water samples containing eserine and carbofuran pesticides, separately. Then in order to observe the sensor behavior of the modified electrode, square wave voltammetry (SWV), electrochemical impedance spectroscopy (EIS), and double potential step chronocoulometry (DPSCC) techniques were used. When the ITO/CuPc-AQ electrode was doped with nano-platinum (nPt) or nano-gold (nAu) particles, the sensitivity of ITO/CuPc-AQ electrode increased. The lowest detection limit (DL) (1.23x10-9 mol dm-3) was obtained with ITO/CuPc-AQ-nAu electrode using electrochemical impedance spectroscopy technique.

An efficient copper phthalocyanine additive of perovskite precursor for improving the photovoltaic performance of planar perovskite solar cells

Abstract Solution processable planar heterojunction perovskite solar cell has drawn much attention as a promising low-cost photovoltaic device, and much effort has been made to improve its power conversion efficiency by choosing appropriate additives for the perovskite precursor solution. Different to those additives reported, a soluble and thermal stable tert-butyl substituted copper phthalocyanine (CuPc(tBu)4) as additive is first introduced into the perovskite precursor solution of a planar perovskite solar cell that is fabricated via the one-step solution process. It is found that the pristine device without CuPc(tBu)4 additive exhibits a power conversion efficiency of 15.3%, while an extremely low concentration (4.4 × 10−3 mM) of CuPc(tBu)4 in the precursor solution leads to the corresponding device achieving an enhanced power conversion efficiency of 17.3%. CuPc(tBu)4 as an additive can improve the quality of perovskite layer with higher crystallinity and surface coverage, then resulting in enhanced light absorption and reduced charge recombination, and thus the better power conversion efficiency. The finding presented here provides a new choice for improving the quality of perovskite layer and the photovoltaic performance of the planar heterojunction perovskite solar cells.

The beneficial effects of mixing spiro-OMeTAD with n-butyl-substituted copper phthalocyanine for perovskite solar cells

Perovskite solar cells have been constructed under ambient conditions by using 2,2',7,7'-Tetrakis-(N,N-di-4-methoxyphenylamino)-9,9'-spirobifluorene (spiro-OMeTAD) mixed with a small quantity of soluble tetra-n-butyl substituted copper phthalocyanine as hole transporting material. The introduction of the phthalocyanine derivative resulted in an impressive increase of cell efficiency, which changed from 10.4% in the absence to 15.4% in the presence of phthalocyanine. This effect is related to the creation of deep traps in the hole transporting phase which block back-travelling electrons as well as to the improvement of the structural quality of the spiro-OMeTAD film in the presence of phthalocyanine. Both functionalities decrease shunt paths within the hole transporting phase resulting in increasing the fill factor and the open-circuit voltage of the cell.

Soluble butyl substituted copper phthalocyanine as alternative hole-transporting material for solution processed perovskite solar cells

Copper phthalocyanine can effectively act as alternative small molecule hole transporting material in perovskite solar cells. In order to produce solution processed devices, a soluble copper phtalocyanine has been synthesized by n-butyl substitution and it was compared to commercially available tert-butyl substituted copper phthalocyanine. It was found that the configuration of the butyl chain plays a very important role in film conductivity and in the subsequent efficiency of solar cells, n-bytyl derivative being the most effective hole transporter. Such a result is due to the fact that n-butyl derivative allows better packing of the molecules in the film and stronger π-π interaction.

Tetra methyl substituted Cu(II) phthalocyanine as alternative hole transporting material for organometal halide perovskite solar cells

Copper phthalocyanine is a promising hole transporting material, which can be employed with solid state perovskite solar cells. Tetra methyl substituted copper phthalocyanine was presently studied as a hole transporting material and demonstrated improved performance with respect to unsubstituted copper phthalocyanine. This material shows a strong absorption in the Visible and Near IR part of the electromagnetic spectrum contributing to the absorption of photons. Its LUMO and HOMO level are favourably positioned for injecting electrons and scavenging holes. Methyl substitution facilitates closer molecular packing leading to a stronger extinction coefficient, stronger Ͽ⿿Ͽ interaction and higher charge carrier mobility.

Spin Exchange Interaction in Substituted Copper Phthalocyanine Crystalline Thin Films.

The origins of spin exchange in crystalline thin films of Copper Octabutoxy Phthalocyanine (Cu-OBPc) are investigated using Magnetic Circular Dichroism (MCD) spectroscopy. These studies are made possible by a solution deposition technique which produces highly ordered films with macroscopic grain sizes suitable for optical studies. For temperatures lower than 2 K, the contribution of a specific state in the valence band manifold originating from the hybridized lone pair in nitrogen orbitals of the Phthalocyanine ring, bears the Brillouin-like signature of an exchange interaction with the localized d-shell Cu spins. A comprehensive MCD spectral analysis coupled with a molecular field model of a σπ − d exchange analogous to sp-d interactions in Diluted Magnetic Semiconductors (DMS) renders an enhanced Zeeman splitting and a modified g-factor of −4 for the electrons that mediate the interaction. These studies define an experimental tool for identifying electronic states involved in spin-dependent exchange interactions in organic materials.

Organic photovoltaic cells with copper (II) tetra-methyl substituted phthalocyanine

Efficient heterojunction organic photovoltaic (OPV) cells are fabricated based on copper tetra-methyl phthalocyanine (CuMePc) as donor and fullerene (C60) as acceptor. The power conversion efficiency of CuMePc/C60 OPV cell (2.52%) is increased by 88% compared with that of the non-peripheral substituted copper phthalocyanine (CuPc)/C60 OPV cell (1.34%). The introduction of methyl substituent leads to stronger π—π interaction of CuMePc (∼ 3.5 Å) than that of CuPc (∼ 3.8 Å). The efficiency improvement is attributed to the enhanced carrier mobility of CuMePc thin film (1.1 × 10−3 cm2/V·s) and better film morphology by introducing methyl groups into the periphery of CuPc molecule.

Phthalocyanines–MWCNT hybrid materials: Fabrication, aggregation and photoconductivity properties improvement

The 2,9,16-trilauryloxy-23-hexyloxy substituted copper phthalocyanines multiwall carbon nanotubes (CuPc(OC 12H 25) 3(OC 6H 13)–MWCNT) hybrid materials were facilely prepared by a chemical functionalization method. The aggregation structures of resulting hybrid materials have been characterized by TEM, SEM, FTIR, XRD and UV–vis measurements. The CuPc(OC 12H 25) 3(OC 6H 13)–MWCNT hybrid materials exhibit good solution storage stability and a low aggregation tendency due to the chemical bonding between MWCNT and asymmetrically substituted phthalocyanines. The enhancement of the photoconductivity of phthalocyanines–MWCNT hybrid materials has been investigated in terms of interaction effects of phthalocyanines and MWCNT. It could supply a new way to fabricate a light energy conversion materials.

Bromine and alkoxyl substituted copper phthalocyanine derivative thin films studied with spectroscopic ellipsometry

Abstract Tetrabromo-tetraalkoxyl substituted copper phthalocyanine (TBTACuPc), tetraalkoxyl substituted copper phthalocyanine (TACuPc) and copper phthalocyanine only (CuPc) thin films were prepared on single-crystal silicon. The optical and dielectric properties of these films were studied on a new type of scanning photometric ellipsometer in which the analyzer and polarizer rotate synchronously. The optical constants, dielectric function and absorption coefficients of these films have been obtained in the wavelength range 500–800 nm. It has been found that the substituted groups on the conjugated phthalocyanine macrocycles strongly influence resonance wavelength and abnormal dispersion of the thin films.

Anodic doping of electropolymerized copper 2,9,16,23-tetraaminophthalocyanine

Anodic polymerization of 2,9,16,23-tetraamino substituted copper phthalocyanine is studied in 0.1 M Bu4NBF4and Bu4NClO4in dimethylformamide (DMF). The electropolymerization rate in DMF is two to three times that in dimethyl sulfoxide, due to a lesser donor ability of DMF and a weaker blocking of radical cations formed during the oxidation of initial copper phthalocyanine. According to a study of the electrochemical behavior of polymerized copper phthalocyanine in neutral aqueous solutions, the anodic doping of the polymer is accompanied by one redox transition. The two redox transitions, observed in an aqueous solution of acid, are explained by two successive steps of oxidation of an aniline-like structure or by the involvement of two protonated systems in the doping process, specifically, a stacked system (phthalocyanine ligands collected in parallel stacks) and a polyaniline system.

Visible Aromatic Electronic Effects Using a Series of Substituted Copper Phthalocyanines

Phthalocyanines provide an opportunity to directly observe electronic effects in an aromatic system through color changes that are dependent on the nature of peripheral substituents. Simple, reliable syntheses of electron-poor and electron-rich phthalocyanines are reported, along with corresponding UV-visible spectra. This is suitable for a sophomore organic course; both synthetic and physical organic principles may be developed by the instructor.

Ferroelectric phase transition in Langmuir-Blodgett films of copper phthalocyanine

A ferroelectric phase transition is observed in Langmuir-Blodgett films prepared from substituted copper phthalocyanine molecules. The linear and nonlinear dielectric properties of the films and the switching of their spontaneous polarization are investigated in the temperature range of the phase transition. The observed features can be explained by the Landau-Ginzburg model of a first-order phase transition.

Supramolecular Assembly Formation in Monolayers of tert-Butyl Substituted Copper Phthalocyanine and Tetrabenzotriazaporphin

The effect is studied of the layer formation conditions on the molecular arrangement of copper tetra- tert-butyl phthalocyanine (CuPctBu4) and copper tetra- tert-butyl tetrabenzotriazaporphin (CuThptBu4) at the air–water interface. The decrease in initial surface concentration of these compounds is shown to affect the molecular orientation, as indicated by the increase in the area per molecule. The data are interpreted in terms of formation of CuPctBu4 and CuThptBu4 monolayers with a ‘face-on’ molecular arrangement when the initial surface concentration is sufficiently small (N less than 1.6 × 10−7 mole/m2 for CuPctBu4 and N less than 4 × 10−7 mole/m2 for CuThptBu4) and changes in the molecular orientation to ‘edge-on’ when the N values are higher. It is emphasized that the ‘edge-on’ orientation on the water surface is not only a molecular but a collective property of the azaporphyrine supramolecular assembly.

High-sensitivity phthalocyanine LB film gas sensor based on field effect transistors

A new kind of symmetrically substituted copper phthalocyanine derivative was synthesized. Metal-oxide-semiconductor field effect transistors (MOSFET) were designed for the measurements of FET characteristics. At the same time, oxide-semiconductor field effect transistors (OSFET) were specially designed with a long gate area for the measurements of gas sensitivity of phthalocyanine LB film. To obtain high sensitivity of the Langmuir–Blodgett (LB) gas sensor, FETs with depletion(D) p-channel mode were selected to be fabricated on the same monolithic silicon. LB multilayer films of copper phthalocyanine (CuPc) were later transferred to the long gate area of OSFET(D), forming the structure of LB-OSFET(D). The measurement of gas sensitivity for the LB-OSFET(D) sensor showed that higher sensitivity to NO 2 could be obtained because of the effect of exhausted mode used in FET. This sensor can detect NO 2 up to 0.1 ppm; it also exhibits good stability, excellent selectivity, and rapid response and recovery.

Direct observation of the stacked structure in substituted copper phthalocyanine LB films with STM

AbstractThe in‐plane molecular structures of octa‐alkyl substituted copper phthalocyanine LB films deposited on graphite have been resolved with a scanning tunnelling microscope (STM). The face‐to‐face stacking of Pc macrocycles has been observed in the topographies of R8PcCu monolayers. The stacking period was found to be 3.8–4 Å and the molecular rows were separated by 19 Å and 16 A for (C6H13)PcCu and (C5H11)PcCu respectively.