Phthalocyanine Sheet Research Articles

Two-dimensional transition metal phthalocyanine sheet as a promising electrocatalyst for nitric oxide reduction: a first principle study.

Electrochemical reduction is a promising technology to treat polluted water contaminated by nitrate and nitrite ions under mild conditions. NO is an important intermediate species and determines selectivity toward different product and rate of whole reaction. However, the most studied NOER electrocatalysts are noble pure metal, which face problems of low utilization and high cost. Herein, by means of density functional theory computations, catalytic performance of 2D TM-Pc sheets (TM = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Nb, Mo, Ru) as NOER catalysts were systematically evaluated. Among all the studied 2D TM-Pc sheets, our results revealed 2D Co-Pc sheet was identified as the best NOER catalyst, for a proper NO absorption energy and its relatively low limiting potential. The final reduction product of NOER is either NH3 at low coverages with energy input of 0.58eV or N2O at high coverages with no energy barrier. Moreover, 2D Co-Pc sheet can efficiently suppress the competing HER. This study could not only provide a new approach for electrochemical denitrification to resolve environmental pollution but also be useful for valuable ammonia production.

Phthalocyanine sheet polymer based amperometric sensor for the selective detection of 2,4-dichlorophenol

Cobalt phthalocyanine sheet polymer (poly-CoPc) was synthesized by the thermal condensation of cobalt tetracarboxylicacid phthalocyanine (CoTCAPc). The synthesized complex and polymer were characterized by 1H NMR, FT-IR, absorption spectroscopy, P-XRD and thermogravimetric analysis. The formation of the polymer was monitored by FT-IR spectra and the peak corresponding to –C=O and –OH of –COOH of CoTCAPc disappeared in poly-CoPc. The polymer showed highly amorphous nature with thermal stability upto 420 °C. The cyclic voltammogram of poly-CoPc exhibited redox-active behavior and the glassy carbon (GC) electrode was modified by immobilizing poly-CoPc (GC/poly-CoPc). The modified electrode was characterized by cyclic voltammetry and impedance spectroscopy and used for the electrochemical detection of 2, 4-dichlorophenol (DCP) using voltammetry and amperometric techniques. The electrocatalytic oxidation of DCP using voltammetric technique showed a linear response in the concentration range 1 to 36 μM with the limit of detection (LOD) 0.350 μM (±0.010 μM) and the sensitivity value of 0.08 μA μM−1. Further, the designed GC/poly-CoPc sensor was used to detect DCP by an amperometric technique which exhibited a linear response in the concentration range 0.5–10 μM with LOD 0.150 μM (±0.005 μM) and sensitivity value 0.0384 μA μM−1. Fabricated sensor displayed greater stability, repeatability, reproducibility and high selectivity towards the detection of DCP. Further, the designed sensor is highly selective towards the detection of DCP even in presence of various aliphatic and aromatic alochols.

Magnetic Properties of One- and Two-Dimensional Functional Materials: Oxygen Molecules Encapsulated in Single-Walled Carbon Nanotubes and Copper Ions Embedded into Phthalocyanine Sheets

Background: In this paper, we report on the topics of one-dimensional (1D) and two-dimensional (2D) functional materials. Single-Walled Carbon Nanotubes (SWCNTs) are seamless hollow cylinders made of hexagonal lattice graphite sheets. The SWCNTs have attracted considerable attention due to the applicability of their enclosed nanospaces to engineering, and many types of guest materials are encapsulated inside their 1D space, expecting unusual properties. The poly Transition Metal (TM) phthalocyanine, in which phthalocyanine units are extended in two dimensions by sharing benzene rings, is one of the examples of the TM containing 2D carbon materials. Because of strong correlation between localized d-electrons in the TM atom and delocalized π-electrons on the poly phthalocyanine frame, it is expected that spin-polarized conduction, which is useful for the spintronic applications. Objectives: The objective of the first work is to synthesize SWCNTs encapsulating oxygen molecules having spin one, whose O-O bond directions are aligned to the longitudinal direction of the SWCNTs. The objective of the second work is to synthesize Poly Cu Phthalocyanine (PCuPc) through a bottom-up method by using copper octacyanophthalocyanine as a building block and to elucidate its crystal structure and magnetic properties. Methods: SWCNTs with inner diameter of ca 0.8 nm were prepared by the CoMoCAT method, and encapsulated together with oxygen molecules (~400 Torr) into a high-purity quartz tube. To subtract the background signals of the SWCNTs and the quartz tube, we prepared the same SWCNTs inducing He gas after evacuating oxygen molecules. Magnetization measurements of these SWCNTs samples were conducted by means of a SQUID magnetometer and a pulse magnet using an induction method. PCuPc were synthesized by a solid state reaction of octacyanophthalocyanine, tetracyanobenzene, and CuCl2·2H2O in glass ampoules sealed after evacuation. The as-synthesized samples were characterized using XRD analysis and TEM microscopy. Magnetization measurement of the samples were done by using a SQUID magnetometer. Results: The intrinsic magnetization data from oxygen molecules inside the SWCNTs (temperature and magnetic field dependence) show magnetic properties typical of the spin-one Heisenberg antiferromagnet named a Haldane magnet. PCuPc and its half-filling counterpart were obtained by solid state reaction. Both magnetic susceptibility and magnetization of PCuPc are larger than those of half-filling PCuPc, but the magnitudes of the former sample are about 1.5 times larger than those of the latter one, which is expected to be twice from the geometric superlattice structure. Conclusion: We have studied magnetic properties (magnetic susceptibility and magnetization) of oxygen molecules encapsulated into Single Walled Carbon Nanotubes (SWCNTs) with diameters of about 0.8 nm, regarded as a 1D functional magnetic material, and Poly Copper Phthalocyanine (PCuPc) and poly half-filling copper phthalocyanine (half-filling PCuPc), regarded as 2D functional magnetic materials.

Magnetic Properties of One- and Two-Dimensional Functional Materials: Oxygen Molecules Encapsulated in Single-Walled Carbon Nanotubes and Copper Ions Embedded into Phthalocyanine Sheets

Magnetic Properties of One- and Two-Dimensional Functional Materials: Oxygen Molecules Encapsulated in Single-Walled Carbon Nanotubes and Copper Ions Embedded into Phthalocyanine Sheets

CO2 Electroreduction Performance of Phthalocyanine Sheet with Mn Dimer: A Theoretical Study

Due to the high surface ratio and dispersed metal sites, organometallic sheets provide a very special platform for catalysis. Here we investigate the CO2 electroreduction performance of expanded phthalocyanine sheets with different transition metal dimers using density functional theory. We have determined Mn dimer to be the best active center, and the reaction path CO2 → COOH* → CO* → CHO* → CH2O* → CH3O* → CH3OH is identified as the preferable one with the overpotential of 0.84 eV. Electronic structures analyses show that σ-bonding−π-backbonding mode exists when COOH* adsorbed on Mn2-Pc, which is different from the bonding mode on Mn-Pc counterpart. Our study indicates that the introduction of metal dimer in porous covalent organic frameworks provides a new strategy for the design of catalytic materials for CO2 electroreduction.

Polymeric phthalocyanine sheets as electrocatalytic electrodes for water-oxidation

Polymeric copper and cobalt phthalocyanine (Cu-pPc and Co-pPc) were prepared as thin films on fluorine-doped tin oxide (FTO) glass from evaporated metal films via a chemical vapor deposition (CVD) process with 1,2,4,5-tetracyanobenzene (TCB). The films were characterized by optical absorption spectroscopy in transmission and by X-ray photoelectron spectroscopy. Different oxidation states of the metal atoms were detected indicating different chemical environments. Reversible electrochemical reduction of Cu-pPc and Co-pPc was observed and monitored by cyclic voltammetry and spectroelectrochemical investigations. Cyclic voltammetry and chronoamperometry in the positive voltage range led to anodic currents in the oxygen evolution reaction that could be performed at stable current densities and showed a remarkable efficiency in particular for electrodes of Co-pPc in this reaction, attractive for the conversion of electrical energy into chemical energy.

Giant magnetocrystalline anisotropy of 5d transition metal-based phthalocyanine sheet.

Large magnetocrystalline anisotropy energy (MAE) is a critical requirement for nanomagnets for applications in magnetic memory and storage devices. Due to small spin-orbit interaction the MAE of ferromagnetic films or single molecule magnets based on 3d metals is small and in typical magnetic nanostructures it is of the order of 2-3 meV. We show that MAE as high as 140 meV can be achieved by applying an external electric field or a biaxial tensile strain to phthalocyanine sheets decorated by 5d transition metal atoms such as Os and Ir. Our observation is based on a systematic study of 5d transition metal absorbed ploy phthalocyanine (Pc) sheets using first-principles density functional theory (DFT) combined with self consistently determined Hubbard U that accounts for the strong correlation energy. We attribute the high MAE values to dxy and dx(2)-y(2) (dxz and dyz) interaction in Ir (Os) adsorbed structure.

Anisotropic Mo2–Phthalocyanine Sheet: A New Member of the Organometallic Family

Metal-organic porous sheets, due to their unique atomic configurations and properties, represent a class of materials beyond graphene and BN monolayers. The Mo2-phthalocyanine-based sheet (Mo2Pc) is a new member of this porous organometallic family. Using density functional theory with hybrid functional for exchange-correlation potential, we show that this dimer-based material, unlike conventional organic monolayers that contain isolated metal atoms, possesses unique mechanical, magnetic, electronic, and optical properties due to inherent anisotropy in the structure. Furthermore, it is a semiconductor with a direct band gap of 0.93 eV and is antiferromagnetic with each Mo site carrying a magnetic moment of 0.88 μB. The strong anisotropy in elasticity and infrared light absorption is likely to open new doors for potential applications.

First-principles investigation of chemical modification on two-dimensional iron—phthalocyanine sheet

Successful synthesis of single iron—phthalocyanie (FePc) framework layer on substrate and its transferrable properties open the door for decorating the separately distributed transition metals for exploring the diverse properties. We have studied the effects of chemical modification on two-dimensional FePc organometallic framework with density functional theory. For simplicity, the non-metal atoms with variant valence electrons are used as prototypes to estimate the effects from chemical modifications with different functional groups. The thermo-stabilities of the non-metal atom decorated complex sheet materials have been estimated by the first-principles constant energy molecular dynamic simulations. Upon the non-metal atom adsorption, the magnetic moment could be changed from 2 μB to 0, 1, 2, and 3 μB per unit cell for the case of tetra-, penta-, hexa-, and hepta-valent non-metal modifications, respectively, showing interesting promise to tailor its magnetic properties for potential applications.

Absorption induced modulation of magnetism in two-dimensional metal-phthalocyanine porous sheets

Metal-phthalocyanine porous sheets have uniformly dispersed metal sites in Pc framework, making absorption happen naturally. Here, we explore the effects of absorption of chlorine atoms on magnetism in transition metal embedded phthalocyanine (poly-TMPc) sheets with TM = Cr, Mn, and Fe. We show that when one Cl is absorbed on the TM, the strong square planar crystal field becomes weak in a square pyramidal configuration and the TM is in the +3 oxidized state, resulting in the magnetic moment of 3, 4, and 5 μB for Cr, Mn, and Fe, respectively, with weak antiferromagnetic couplings. When another Cl is introduced to the TM on the other side, it extracts one electron from the Pc framework making the substrate p-doped. The magnetic coupling is antiferromagnetic for poly-CrPc-2Cl and the poly-FePc-2Cl, while it becomes ferromagnetic for poly-MnPc-2Cl, suggesting that absorption can effectively modulate the bonding environment and tune the magnetic properties of the systems, and the controlled absorption can be used to tailor materials.

Pre-combustion CO2 capture by transition metal ions embedded in phthalocyanine sheets

Transition metal (TM) embedded two-dimensional phthalocyanine (Pc) sheets have been recently synthesized in experiments [M. Abel, S. Clair, O. Ourdjini, M. Mossoyan, and L. Porte, J. Am. Chem. Soc. 133, 1203 (2010)], where the transition metal ions are uniformly distributed in porous structures, providing the possibility of capturing gas molecules. Using first principles and grand canonical Monte Carlo simulations, TMPc sheets (TM = Sc, Ti, and Fe) are studied for pre-combustion CO(2) capture by considering the adsorptions of H(2)/CO(2) gas mixtures. It is found that ScPc sheet shows a good selectivity for CO(2), and the excess uptake capacity of single-component CO(2) on ScPc sheet at 298 K and 50 bar is found to be 2949 mg/g, larger than that of any other reported porous materials. Furthermore, electrostatic potential and natural bond orbital analyses are performed to reveal the underlying interaction mechanisms, showing that electrostatic interactions as well as the donation and back donation of electrons between the transition metal ions and the CO(2) molecules play a key role in the capture.

GC–MS studies on degradation of copper phthalocyanine sheet polymer

Synthetic metal phthalocyanine sheet polymer of copper showed exceptional thermal stability with maximum polymer decomposition temperature (PDT max) 525 °C in air and 760 °C in nitrogen with char yield 91% at 800 °C in nitrogen atmosphere. Because of its excellent thermal stability, MS and GC–MS studies found to be very difficult. The present work deals with GC–MS studies on this copper phthalocyanine sheet polymer at various temperatures in the range 500–1000 °C. Tentative mechanisms for its modes of fragmentation are proposed and most probable degradation products are identified based on GC–MS studies.

Characterization of cobalt phthalocyanine sheet polymer by gas chromatography mass spectrometry on its pyrolysis products

Cobalt phthalocyanine sheet polymer showed very high-thermal stability with a maximum polymer decomposition temperature of 500 °C in air, and 860 °C in nitrogen, with char yield of 85% at 800 °C in a nitrogen atmosphere. MS and GC–MS studies of the cobalt phthalocyanine sheet polymer were conducted at high temperatures ranging from 500 to 1000 °C. Tentative mechanisms are proposed for its modes of fragmentations and the most probable degradation products were identified by GC–MS.

Studies on phthalocyanine sheet polymers

Cobalt, nickel and copper phthalocyanine sheet polymers are synthesized by heating their respective metal (II) phthalocyanine tetracarboxylic acids at 400 °C in nitrogen atmosphere. These polymers are characterized using UV–Visible spectra, IR spectra, magnetic susceptibility, X-ray powder diffraction and thermogravimetric analysis. Electrical conductivity studies are carried out using two-probe technique in the temperature range 25–200 °C for each polymer. These polymeric materials showed room temperature electrical conductivity 10–1000 times higher values compared to earlier reported values for this type of sheet polymers.

Degradation study on the thermally stable nickel phthalocyanine sheet polymer

Poly (nickel phthalocyanine) which has exceptional thermal stability is synthesized. Knowledge of modes of degradation of this polymer is found to be necessary for its high temperature applications. This polymer showed very high thermal stability with maximum polymer decomposition temperatures (PDT max) of 500 °C in air and 890 °C in N 2, with char yield 93% at 800 °C. Because of its excellent thermal stability, degradation study with MS as well as GC–MS techniques were found to be very difficult. The present publication deals with MS and GC–MS studies of nickel phthalocyanine sheet polymer at high temperatures ranging from 700 to 1000 °C. Tentative mechanisms are proposed for its modes of fragmentations and based on GC–MS studies, the most probable degradation products are identified.

X‐Ray photoelectron spectroscopy and electrical conductivity studies of metallophthalocyanine sheet polymers

AbstractThe X‐ray photoelectron spectroscopy (XPS) technique has been used to characterize metallophthalocyanine sheet polymers having peripheral carboxyl groups. A comparative analysis of the XPS and electrical conductivity data of metal‐free, and nickel‐ and copper‐containing, phthalocyanine sheet polymers has been described. Metallophthalocyanine sheet polymers exhibited a maximum conductivity of about 1 S cm−1 on pyrolysis.

Organic semiconductors—metal phthalocyanine sheet polymers

AbstractThis publication discusses the electronic, magnetic susceptibility, MS and GC–MS pyrolysis, X‐ray powder diffraction, and electrical conductivity studies on metal phthalocyanine sheet polymers. The magnetic measurements over the range of magnetic field strengths 1025–6144 gauss indicated the absence of the intermolecular cooperative effect. MS and GC–MS studies indicate that all these metal phthalocyanine sheet polymers give benzene, cyanobenzene, and dicyanobenzene on thermal degradation. The electrical conductivity measurements showed that these polymers are semiconductor in nature.

Phthalocyanine polymers. II. Synthesis and characterization of some metal phthalocyanine sheet oligomers

AbstractMetal phthalocyanine oligomers that possess peripheral carboxylic acid groups were prepared by the reaction of pyromellitic dianhydride, a metal salt, urea, and a catalyst. These materials have blue to purple colors with a metallic luster and are soluble in sulfuric acid, dimethylsulfoxide, dimethylformamide, and dimethylacetamide. Their thermal stability is high in an anaerobic atmosphere with char yields of 80–85% at 800°C. Elemental, spectral, and titrimetric analyses and thermal studies were carried out to characterize them.