The effect of protonation on the spectra and stabilities of alkoxyl substituted phthalocyaninatometals

The protonation abilities of phthalocyaninatometals (MPcs) increase but their stabilities reduce by the introduction of alkoxyl substituents at alpha position. In the toluene, the order of mono-protonation rate for the tetra-alpha-(2, 2, 4-trimethyl-3-pentoxy)phthalocyaninatometals sorts with the center metals is Zn>Co>Cu>Ni>Fe, which is opposite to the order of their wavelength difference between the Q bands and X bands. However, their mono-protonated species can be decomposed easily at the rate order FePc>CoPc>CuPc>NiPc>ZnPc, analogous to their decomposition abilities in the benzoylperoxide (BPO) oxidation. In addition, it is interesting that a more remarkable decomposition is found when partial CuPc was mono-protonated.     

Correlation between molecular orbitals and doping dependence of the electrical conductivity in electron-doped metal-phthalocyanine compounds

We have performed a comparative study of the electronic properties of six different electron-doped metal-phthalocyanine (MPc) compounds (ZnPc, CuPc, NiPc, CoPc, FePc, and MnPc), in which the electron density is controlled by means of potassium intercalation. Despite the complexity of these systems, we find that the nature of the underlying molecular orbitals produces observable effects in the doping dependence of the electrical conductivity of the materials. For all the MPc's in which the added electrons are expected to occupy orbitals centered on the ligands (ZnPc, CuPc, and NiPc), the doping dependence of the conductivity has an essentially identical shape. This shape is different from that observed in MPc materials in which electrons are also added to orbitals centered on the metal atom (CoPc, FePc, and MnPc). The observed relation between the macroscopic electronic properties of the MPc compounds and the properties of the molecular orbitals of the constituent molecules clearly indicates the richness of the alkali-doped metal-phthalocyanines as a model class of compounds for the investigation of the electronic properties of molecular systems.     

Metal—ligand and π singlet—triplet transitions in phthalocyanine films studied by inelastic electron tunneling spectroscopy

Inelastic electron tunneling spectroscopy (IETS) on AlAl₂O₃/PcPb tunneling junctions at 4.2 K has been used to study electronic transitions involving π, π^≠ and metal-ligand orbitals of phthalocyanine (Pc) films (H₂Pc, FePc, CoPc, NiPc, CuPc, ZnPc). The results are compared with calculations for Pc molecules.     

Microwave-assisted synthesis and characterization and theoretical calculations of the first example of free and metallophthalocyanines from salen type Schiff base derivative bearing thiophen and triazole heterocyclic rings

Novel metal-free and metallophthalocyanine complexes of Co, Ni, Cu, and Zn have been synthesized by exposure to microwave irradiation and reflux conditions and the products purified by several techniques. The newly prepared compounds have been characterized by elemental analyses, IR, ¹H NMR, MS and UV-Vis spectroscopy. Furthermore, theoretical calculations of metallophthalocyanines CuPc, NiPc, ZnPc and CoPc were carried out to comparatively describe the molecular structures, molecular orbital and UV-Vis spectra of metallophthalocyanine complexes by the HF theory. A comparison between the different molecules for the geometry, molecular orbitals was made. The simulated order of the sizes of the central hole was CoPc > NiPc < CuPc < ZnPc, which is in complete accord with the experiment. Moreover, the HOMO-LUMO gaps were varied in order of CoPc > NiPc > ZnPc > CuPc. The calculated structures, electronic absorption spectra of metallophthalocyanine complexes are in good consistency with the experimental results.     

Investigation of Spectroscopic and Optoelectronic Properties of Phthalocyanine Molecules

Russian Journal of General Chemistry - Thin-film structural, electrical and optical characteristics of some phthalocyanines (ZnPc, NiPc, CoPc, CuPc and LiPc) were studied by UV-visible spectroscopy...     

Theoretical studies on the structures and vibrational spectra of Ni, Pd, and Pt phthalocyanines

Electronic structure calculations and spectroscopic assignments for metallophthalocyanines NiPc, PdPc and PtPc are performed on optimized geometries at B3LYP/LANL2DZ level. The order of the sizes of the central hole is computed to be PdPc > PtPc > NiPc, with the hole size of PdPc close to that of PtPc. The Mulliken charges of the central M vary in the order of PtPc > NiPc > PdPc, and the HOMO-LUMO gaps are in the order of NiPc < PdPc < PtPc, in agreement with the experimental result. The simulated IR spectra for the three derivatives are compared with the experimental absorption spectra, and very good consistency has been obtained. The simulated medium intensity bands associated with the metal-ligand vibrations which appear as singlet bands at 880, 877 and 883 cm⁻¹, respectively, exhibit the order of PtPc > NiPc > PdPc, which is the same order as experiment. Furthermore, the metal-ligand vibrational bands for Raman spectra shift in the order NiPc > PtPc > PdPc. The strongest Raman lines predicted at 1562, 1532 and 1534 cm⁻¹ for NiPc, PdPc and PtPc are very sensitive to the metal ion.     

Magnetism of phthalocyanine-based organometallic single porous sheet

A two-dimensional (2D) periodic Fe phthalocyanine (FePc) single-layer sheet has very recently been synthesized experimentally (Abel, M.; et al. J. Am. Chem. Soc.2011, 133, 1203), providing a novel pathway for achieving 2D atomic sheets with regularly and separately distributed transition-metal atoms for unprecedented applications. Here we present first-principles calculations based on density functional theory to investigate systematically the electronic and magnetic properties of such novel organometallics (labeled as TMPc, TM = Cr-Zn) as free-standing sheets. Among them, we found that only the 2D MnPc framework is ferromagnetic, while 2D CrPc, FePc, CoPc, and CuPc are antiferromagnetic and 2D NiPc and ZnPc are nonmagnetic. The difference in magnetic couplings for the studied systems is related to the different orbital interactions. Only MnPc displays metallic d(xz) and d(yz) orbitals that can hybridize with p electrons of Pc, which mediates the long-range ferromagnetic coupling. Monte Carlo simulations based on the Ising model suggest that the Curie temperature (T(C)) of the 2D MnPc framework is ～150 K, which is comparable to the highest T(C) achieved experimentally, that of Mn-doped GaAs. The present study provides theoretical insight leading to a better understanding of novel phthalocyanine-based 2D structures beyond graphene and BN sheets.     

Weak epitaxy growth and phase behavior of planar phthalocyanines on p-sexiphenyl monolayer film

We systematically investigated the weak epitaxy growth (WEG) behavior of a series of planar phthalocyanine compounds (MPc), i.e., metal-free phthalocyanine (H2Pc), nickel phthalocyanine (NiPc), copper phthalocyanine (CuPc), zinc phthalocyanine (ZnPc), iron phthalocyanine (FePc), cobalt phthalocyanine (CoPc), grown on a p-sexiphenyl ( p-6P) monolayer film by selected area electron diffraction (SAED) and atomic force microscopy (AFM). Two types of epitaxial relations, named as incommensurate epitaxy and commensurate epitaxy, were identified between phthalocyanine compounds and the substrate of the p-6P film. The tiny variation of the lattice constant of phthalocyanine compounds can result in different crystal orientations. The change rule of incommensurate and commensurate epitaxy was extracted. The tendency of commensurate epitaxy becomes weaker as the lattice constant b increases, while it gets stronger as the substrate temperature is elevated. Large size and continuous H2Pc films can be obtained by controlling the growth conditions. The WEG method is generally applicable in the whole family of planar phthalocyanine compounds and may be used to fabricate other high-quality organic films.     

Molecular structure, IR spectra of 2-mercaptobenzothiazole and 2-mercaptobenzoxazole by density functional theory and ab initio Hartree–Fock calculations

Quantum chemistry calculations have been performed using Gaussian03 program to compute optimized geometry, harmonic vibrational frequency along with intensities in IR and Raman spectra and atomic charges at RHF/6-31+G*, B3LYP/6-31+G* and B3LYP/6-31++G* levels for 2-mercaptobenzothiazole (MBT, C₇H₅NS₂) and 2-mercaptobenzoxazole (MBO, C₇H₅NOS) in the ground state. The scaled harmonic vibrational frequencies have been compared with experimental FT-IR and FT-Raman spectra. The results show that the scaled theoretical vibrational frequencies is very good agreement with the experimental values. A detailed interpretation of the infrared and Raman spectra of 2-mercaptobenzothiazole and 2-mercaptobenzoxazole was reported. Comparison of calculated spectra with the experimental spectra provides important information about the ability of the computational method to describe the vibrational modes.     

Distribution and structure of N atoms in multiwalled carbon nanotubes using variable-energy X-ray photoelectron spectroscopy

We investigated the inhomogeneous distribution of concentration and electronic structure of the nitrogen (N) atoms doped in the multiwalled carbon nanotubes (CNTs) by variable-energy X-ray photoelectron spectroscopy (XPS), X-ray absorption near-edge structure, and electron energy-loss spectroscopy. The vertically aligned N-doped CNTs on the substrates were grown via pyrolysis of iron phthalocyanine (FePc), cobalt phthalocyanine (CoPc), and nickel phthalocyanine (NiPc) in the temperature range 750-1000 degrees C. They usually have a bamboo-like structure, and the diameter is in the range of 15-80 nm. As the photon energy of XPS increases from 475 to 1265 eV, the N content increases up to 8 atomic %, indicating a higher N concentration at the inside of nanotubes. We identified three typed N structures: graphite-like, pyridine-like, and molecular N(2). The pyridine-like N structure becomes significant at the inner walls. Molecular N(2) would exist as intercalated forms in the vicinity of hollow inside. The XPS valence band analysis reveals that the pyridine-like N structure induces the metallic behaviors. The CNTs grown using NiPc contain the higher content of pyridine-like structure compared to those grown using FePc and CoPc, so they exhibit more metallic properties.     

Infrared spectroscopy of N-methylacetamide in water from high-level QM/MM calculations简

The infrared(IR) spectra of the N-methylacetamide molecule in water are calculated by using the MD simulation with high-level QM/MM corrections. The B3LYP and MP2 levels with 6-311++G** basis set are used for the QM region, respectively. Our results show all IR spectra at the B3LYP level are well consistent with the corresponding MP2 results. A dynamical charge fluctuation is observed for each atom along the simulation trajectories due to the electrostatic polarization(EP) effects from surrounding solvent environment. We find that the QM/MM corrected IR spectra satisfactorily reproduce the experimental vibrational features of amide I–III modes.     

Synthesis, characterization, crystal structure and DFT studies on 3-(1H-benzo[d][1,2,3]triazol-1-yl)-1-oxo-1-m-tolylpropan-2-yl-nicotinate

3-(1H-Benzo[d][1,2,3]triazol-1-yl)-1-oxo-1-m-tolylpropan-2-yl-nicotinate (BOTN) has been synthesized and characterized by elemental analysis, IR, UV-vis and fluorescence spectroscopy. Its crystal structure has also been determined by X-ray single crystal diffraction. For BOTN, density functional theory (DFT) calculations of the structure and vibrational frequencies have been performed at B3LYP/6-311G** level. The comparisons between the experimental vibrational frequencies and the predicted data show that B3LYP/6-311G** method can simulate the IR of BOTN on the whole. Based on the vibration analysis, thermodynamic properties of BOTN have been calculated. The correlative equations between the thermodynamic properties and the temperatures have also been listed. The experimental UV-vis spectra present two peaks and theoretical UV-vis spectra obtained by TD-DFT method exhibit three peaks. The comparison between them suggests that the B3LYP/6-311G** method can only approximately simulate the UV-vis spectra of BOTN. The fluorescence determination reveals two emission bands at 423 and 489 nm, respectively.     

Revised vibrational band assignments for the experimental IR and Raman spectra of 2,3,4-trifluorobenzonitrile based on ab initio, DFT and normal coordinate calculations

In the present study, a systematic vibrational spectroscopic investigation for the experimental IR and Raman spectra of 2,3,4-trifluorobenzonitrile (TFB), aided by electronic structure calculations has been carried out. The electronic structure calculations – ab initio (RHF) and hybrid density functional methods (B3LYP) – have been performed with 6-31G* basis set. Molecular equilibrium geometries, electronic energies, IR intensities, harmonic vibrational frequencies, depolarization ratios and Raman activities have been computed. The results of the calculations have been used to simulate IR and Raman spectra for TFB that showed excellent agreement with the observed spectra. Potential energy distribution (PED) and normal mode analysis have also been performed. The assignments proposed based on the experimental IR and Raman spectra have been reviewed. A complete assignment of the observed spectra has been proposed.     

Comparative density functional theory study of the structures and properties of metallophthalocyanines of group IV B

Density functional theory (DFT) calculations were carried out to comparatively describe the molecular structures, molecular orbital energy gaps, atomic charges, infrared (IR) and Raman spectra of lead phthalocyaninate (PbPc), tin phthalocyaninate (SnPc), germanium phthalocyaninate (GePc), tin (IV) dichlorophthalocyaninate (PcSnCl₂), and germanium (IV) dichlorophthalocyaninate (PcGeCl₂). The calculated structural data and the simulated IR spectrum of PbPc correspond well with the experimental result. The important effects of axial ligands and ionic radius of metal center to the molecular structures, molecular orbital and atomic charges are described, and the metal-sensitive peaks in the IR and Raman spectra are identified by comparative study of the five complexes with different central metals and axial ligands.     

Molecule-substrate interaction channels of metal-phthalocyanines on graphene on Ni(111) surface

Molecule-substrate interaction channels of metal-phthalocyanines (MPcs, including NiPc, CuPc, ZnPc, FePc, and CoPc) on graphene on Ni(111) were investigated by employing high-resolution electron energy loss spectroscopy (HREELS). Except the expected IR-active modes, some Raman-active modes were also observed in all of MPcs, which are considered in this study. From the origination of the Raman-active features, it was deduced that MPcs are coupled with the substrate mainly through their central metal atom. The Raman-active modes appear as symmetric peaks in the HREELS in the case of MPcs with Ni, Cu, and Zn, whereas they are asymmetric and appear as a Fano line shape in the case of MPcs with Fe and Co. This spectroscopic difference indicates that the molecule-substrate coupling is completely different in the two cases mentioned above. The molecule-substrate interaction strength is considerably weak and comparable with the π-π interaction between molecules in the case of MPcs with Ni, Cu, and Zn, whereas it is much stronger in the case of MPcs with Fe and Co. From the HREELS observations, it can be suggested that the whole molecule can be effectively decoupled from the underneath Ni(111) by inserting a single layer of graphene between them in the case of MPcs with Ni, Cu, and Zn, whereas only benzene rings can be completely decoupled in the case of MPcs with Fe and Co.     

硅胶键联MPc的制备及其在氧活化中的作用

过渡金属酞等配合物（MPC）用手均相液相氧化中作催化剂已有不少报导，象许多均相催化剂一样，MPC用于均相反应存在着难于从反应体系中分离出来的问题．把均相配合物催化剂固载在无机氧化物如硅股或有机高分子载体上是解决这一问题的一种方法．我们曾尝试把MP。固载在分子筛载体和硅胶载体上，并用ESR研究其对O2的活化作用[1，2]．本文报导MPc通过共价键键联固载在SiO2上，并研究其对O2的活化作用．1实验部分1．1试剂HSIC13为日本东京化成株式会社产品，二级试剂·发烟硫酸（SO。质量分数大于20％）为分析纯试剂．PCl5为化学纯试…     

Temperature study of Raman, FT-IR and photoluminescence spectra of ZnPc thin layers on Si substrate

The temperature study of zinc phthalocyanine (ZnPc) thin layers deposited on (0 0 1) Si substrate using Raman, FT-IR absorption and photoluminescence (PL) methods are reported. The Raman scattering spectra of ZnPc layers were investigated in the spectral range 1250–1650 cm⁻¹ and in the temperature range 100–500 K. The changes of spectral parameters such as the band position, integrated intensity and full width at half maximum (FWHM) of selected Raman modes while heating and cooling processes have been determined. The fast decrease of the frequency and the intensity of these modes observed with the increase of the temperature above 420 K, can be probably caused by the change of crystalline form of ZnPc thin layer. The FT-IR measurements have been performed in the temperature range 98–523 K. Our study allowed us to estimate the orientation of the molecular plane similar to these of CuPc thin films deposited on Si substrate. The Raman spectra have been compared with FT-IR spectra of ZnPc molecules in KBr pellets and thin layers of ZnPc on (0 0 1) Si substrate. The PL spectra of ZnPc layers were measured in the spectral range 350–1200 nm and in the temperature range 13–320 K. With increasing temperature from 13 to 175 K we observed the increase of PL bands at 1.76 and 1.85 eV which disappear reaching temperature above 200 K.     

Ambient temperature oxygen sensors based on fluoride solid electrolyte: the roles of the constituents in the sensing electrode mixtures containing phthalocyanines

The short-circuit-current response properties of ambient temperature oxygen sensors of the type, Ag|Ag(6)I(4)WO(4)|PbSnF(4)(PSF)| sensing electrode (SE), O(2); SE: mixtures of Pt-black/Pc's/PSF, carbon/Pc's/PSF, Pc's/PSF, Pt-black/PSF, carbon/PSF (phthalocyanines, Pc's: FePc, CoPc, CuPc, H(2)Pc) have been examined to elucidate the roles of the incorporated Pc's, Pt-black and carbon. FePc and CoPc act as the catalyst for the SE-reaction involving the two-electron reduction of oxygen, whereas CuPc and H(2)Pc have not such a catalytic action. The difference is related to the types of the first oxidation of Pc's, i.e. the central metal oxidation and the ligand oxidation. In addition, the sensitivity (S) and 90% response time (t(90)) depend on the oxidation potentials. FePc is the best of the Pc's used here in terms of t(90) (i.e. 40 s for the SE-mixtures of Pt-black/FePc/PSF and carbon/FePc/PSF). Although Pt-black acts as the catalyst, it tends to give rise to hysteresis, drifts and slow response. The undesirable effects are lessened by incorporating Pc's. For the Pt-black/FePc/PSF sensor, the response properties are almost dominated by the incorporated FePc and hence are comparable to those of the C/FePc/PSF sensors. This indicates that Pt-black can be substituted by carbon materials. The incorporated carbon has no such catalytic action. The role is to make the SE-mixtures more electronically conductive, resulting in the improvement of S and t(90).     

IR and Raman Vibrational Assignments for Metal-free Phthalocyanine from Density Functional B3LYP／6-31G（d） Method

Vibrational (IR and Raman) spectra for the metal-free phthalocyanine (H2Pc) have been comparatively investigated through experimental and theoretical methods. The frequencies and intensities were calculated at density functional B3LYP level using the 6-3 IG(d) basis set. The calculated vibrational frequencies were scaled by the factor 0.9613 and compared with the experimental result. In the IR spectrum, the characteristic IR band at 1008.cm^-1 is interpreted as C-N (pyrrole) in-plane bending vibration, in contrast with the traditional assigned N-H in-plane or out-of-plane bending vibration. The band at 874 cm^-1 is attributed to the isoindole deformation and aza vibration. In the Raman spectrum, the bands at 540, 566, 1310, 1340, 1425, 1448 and 1618 cm^-1 are also re-interpreted. Assignments of vibrational bands in the IR and Raman spectra are given based on density functional calculations for the first time. The present work provides valuable information to the traditional empirical assignment and will be helpful for further investigation of the vibration spectra of phthalocyanine analogues and their metal complexes.     

Molecular structure, vibrational spectra and NBO analysis of phenylisothiocyanate by density functional method

The molecular geometry, vibrational frequencies and NBO analysis of phenylisothiocyanate (PITC) in the ground state have been calculated by using density functional theory calculation (B3LYP) with 6-311++G(d,p) basis set. The optimized geometrical parameters obtained by DFT calculations are in good agreement with experimental values. Comparison of the observed fundamental vibrational frequencies of the PITC and calculated result by density functional theory (B3LYP) indicates B3LYP is superior for molecular vibrational problems. The entropy of the title compound was also performed at HF/B3LYP/6-311++G(d,p) levels of theory. Natural bond orbital (NBO) analysis of title molecule is also carried out. A detailed interpretation of the IR and Raman spectra of PITC is reported on the basis of the calculated potential energy distribution (PED). The theoretical spectrogram for IR spectrum of the title molecule has been constructed.