Thin films of unsubstituted and fluorinated palladium phthalocyanines: structure and sensor response toward ammonia and hydrogen

In the present work, we study and compare the structure and sensing properties of thin films of unsubstituted palladium phthalocyanine (PdPc) and hexadecafluorosubstituted palladium phthalocyanine (PdPcF16). Thin films of PdPc and PdPcF16 were obtained by the method of organic molecular beam deposition and their structure was studied using UV-visible spectroscopy, X-ray diffraction and atomic force microscopy techniques. The electrical sensor response of PdPc films toward ammonia and hydrogen was investigated and compared with that of PdPcF16 films. The nature of interaction between the phthalocyanines films and some gaseous analyte molecules has been clarified using Quantum chemical (DFT) calculations

Interaction of metal phthalocyanines with carbon zigzag and armchair nanotubes with different diameters

Quantum-chemical calculations of the association of metal free, cobalt, copper and zinc phthalocyanines (MPc) with carbon zigzag and armchair nanotubes (CNTs) with diameters in the range of 7–14 Å were carried out by the DFT method with the use of BH van der Waals density functional and DZP atomic basis set. It was shown that interaction energy between the phthalocyanine molecules and the CNTs, as a whole, increases with an increase of the diameter of carbon nanotubes. However, in the case of CNT(n,0) the energy reaches its maximal value at n = 16 or 17 depending on the central metal atom and phthalocyanine orientation on the carbon nanotubes surface. Up to diameter of 10.5 Å of the CNTs, stronger binding of the considered MPc macrocyclic molecules is observed with carbon armchair nanotubes. However, in the case of higher diameters the phthalocyanines are associated more strongly with the zigzag CNTs

Effect of fluorosubstitution on the structure of single crystals, Effect of fluorosubstitution on the structure of single crystals,thin films and spectral properties of palladium phthalocyanines

In this work, the crystalline structure of single crystals grown by vacuum sublimation of unsubstituted palladium phthalocyanines (PdPc), its tetrafluorinated (PdPcF4) and hexadecafluorinated (PdPcF16) derivatives have been investigated using X-ray diffraction measurements. Two crystalline phases have been identified for PdPc; the molecules in both phases crystallize in stacks with herringbone arrangement in the monoclinic space groups (C2/c for -PdPc; P21/n for -PdPc). Both PdPcF4 and PdPcF16 crystallize in the triclinic P-1 space group, forming stacks of molecules in columnar arrangement with molecules in adjacent columns are aligned parallel to one another. X-ray diffraction measurements have also been used to elucidate the structural features and molecular orientation of thin films of PdPc, PdPcF4 and PdPcF16, grown by organic molecular beam deposition at different substrate temperatures. The effect of fluorosubstitution on UV-visible optical absorption and vibrational spectra of palladium phthalocyanine derivatives is also discussed

Molecular and Electonic Structure of Benzoporphyrins with Iron (II) at the Ground Spin State

Квантово-химическим методом теории функционала плотности B3LYP/6-31G(p,d) рассчитано молекулярное и электронное строение моно-, ди-, три- и тетрабензопорфиринатов железа (II). Показано, что основным для них является триплетное электронное спиновое состояние. При этом энергия его квантового выхода всех соединений, за исключением цис-формы дибензопоририната железа (II), достаточна для генерации синглетного кислорода. Наименьшее значение длины волны в спектре поглощения рассмотренных структур находится в интервале 446-550 нм. Данные факты благоприятны для практического использования производных бензопорфиринатов железа (II) для фотодинамической терапии раковых заболеванийMolecular and electronic structure of mono-, di-, tri- and tetrabenzoporphyrins with iron (II) was carried out by quantum-chemical method of density functional theory B3LYP/6-31G(p,d). It was shown that triplet electronic spin state is a ground state for them. The energy of quantum yield of this state for all compounds excluding cis-configuration of iron-dibenzoporphyrin is enough to singlet oxygen formation. The smallest wavelength in adsorption spectra of examined structures has a place in the interval of 446-550 nm. These facts are preferable for practice use of iron-benzoporphyrin derivatives for photodynamic therapy of cancer disease

Molecular and Electonic Structure of Benzoporphyrins with Iron (II) at the Ground Spin State

Квантово-химическим методом теории функционала плотности B3LYP/6-31G(p,d) рассчитано молекулярное и электронное строение моно-, ди-, три- и тетрабензопорфиринатов железа (II). Показано, что основным для них является триплетное электронное спиновое состояние. При этом энергия его квантового выхода всех соединений, за исключением цис-формы дибензопоририната железа (II), достаточна для генерации синглетного кислорода. Наименьшее значение длины волны в спектре поглощения рассмотренных структур находится в интервале 446-550 нм. Данные факты благоприятны для практического использования производных бензопорфиринатов железа (II) для фотодинамической терапии раковых заболеванийMolecular and electronic structure of mono-, di-, tri- and tetrabenzoporphyrins with iron (II) was carried out by quantum-chemical method of density functional theory B3LYP/6-31G(p,d). It was shown that triplet electronic spin state is a ground state for them. The energy of quantum yield of this state for all compounds excluding cis-configuration of iron-dibenzoporphyrin is enough to singlet oxygen formation. The smallest wavelength in adsorption spectra of examined structures has a place in the interval of 446-550 nm. These facts are preferable for practice use of iron-benzoporphyrin derivatives for photodynamic therapy of cancer disease

Excited Electronic States of Porphyrin-Fullerene Dyads with Different Type of Bonding

Основными требованиями к искусственным фоточувствительным системам являются погло- щение света в видимой области спектра, возможность образовывать долгоживущие возбуж- денные электронные состояния и системы с разделенными зарядами. В качестве потенциаль- ных материалов, обладающих указанными свойствами, рассматриваются донорно-акцепторные диады порфирин-фуллерен. В работе представлены результаты квантово-химических расчетов методом теории функционала плотности геометрии, основных и возбуждённых электронных состояний данных объектов с двумя типами связывания: порфирин и фуллерен связаны ковалент- но и ковалентно не связаны, а взаимодействуют посредством межмолекулярных сил. Показано, что в первом случае образование систем с разделенными зарядами происходит более вероятно, чем во втором, но при этом время жизни возбужденных состояний значительно меньше.The general requirements to the artificial photosensitive systems are the light sorption at the visible field of spectrum, the long excitation states lifetime and the possibility to form system with separated charges. Donor-acceptor dyads porphyrin-fullerene are considered as promising materials possessed of noted features. The quantum-chemical calculations? results of geometry, general and excited electronic states of such structures with two kinds of bonds (porphyrin and fullerene are bonded covalently and non-covalently) are presented in this work. It has been shown that formation of system with separated charges in the first case happens more probably than in the second case, but the lifetimes of their excited states sufficiently lower

The Nature of Chemical Bonding of Scandium and Titanium Atoms with Graphene Cluster Models Curved by the Presence of Five- and Seven-Fold Carbon Rings

Квантово-химическим методом теории функционала плотности B3LYP/6-31G(p,d) рассчитано молекулярное и электронное строение кластерных моделей графена, искривлённых из-за наличия пяти- и семичленных углеродных колец. Показано, что атомы скандия и титана наиболее предпочтительно взаимодействуют с данными кольцами, чем с шестичленными. При этом атомы металла выступают в качестве доноров, а углеродные кластеры - в качестве акцепторов электрона. Наиболее прочное связывание скандия и титана с пяти- и семичленными кольцами обусловлено тем, что их атомы углерода дают больший вклад в формирование нижних вакантных молекулярных орбиталей кластеров, принимающих электрон с атомов металлов при взаимодействии, чем атомы сопряжённых с ними шестичленных колец.Molecular and electronic structure of graphene cluster models curved by the presence of five- and seven-fold carbon rings was carried out by quantum-chemical method of density functional theory B3LYP/6-31G(p,d). It was shown that scandium and titanium atoms interact more preferable with these rings than with six-fold ones. At the same time metal atoms act as electron donors, and carbon clusters act as acceptors. Much stronger binding of scandium and titanium by the five- and seven-fold rings can be explained by a fact that their carbon atoms contribute more considerably to the generation of lowest unoccupied molecular orbitals of clusters, accepting electron from metal atoms at the interaction, than atoms of six-fold rings conjugated with other two mentioned types of rings

Nanotube-derived carbon foam for hydrogen sorption

A new kind of carbon foam, which is based on the welding of single-walled carbon nanotubes, is built in a computer simulation. Its precisely defined architecture and all atomic positions allow one to perform detailed theoretical analysis of the properties. Such foam is as light as 1/9 of steel, while its stiffness is similar and nearly isotropic, and it represents a strong three-dimensional material with various possible applications. Furthermore, its nanoporous structure is accessible to molecular hydrogen and the potential surface analysis indicates that it should be an excellent hydrogen storage medium. Importantly, such foam is a feasible structure that can be produced based on the known tube/fullerene welding techniques

The Nature of Chemical Bonding of Scandium and Titanium Atoms with Graphene Cluster Models Curved by the Presence of Five- and Seven-Fold Carbon Rings

Квантово-химическим методом теории функционала плотности B3LYP/6-31G(p,d) рассчитано молекулярное и электронное строение кластерных моделей графена, искривлённых из-за наличия пяти- и семичленных углеродных колец. Показано, что атомы скандия и титана наиболее предпочтительно взаимодействуют с данными кольцами, чем с шестичленными. При этом атомы металла выступают в качестве доноров, а углеродные кластеры - в качестве акцепторов электрона. Наиболее прочное связывание скандия и титана с пяти- и семичленными кольцами обусловлено тем, что их атомы углерода дают больший вклад в формирование нижних вакантных молекулярных орбиталей кластеров, принимающих электрон с атомов металлов при взаимодействии, чем атомы сопряжённых с ними шестичленных колец.Molecular and electronic structure of graphene cluster models curved by the presence of five- and seven-fold carbon rings was carried out by quantum-chemical method of density functional theory B3LYP/6-31G(p,d). It was shown that scandium and titanium atoms interact more preferable with these rings than with six-fold ones. At the same time metal atoms act as electron donors, and carbon clusters act as acceptors. Much stronger binding of scandium and titanium by the five- and seven-fold rings can be explained by a fact that their carbon atoms contribute more considerably to the generation of lowest unoccupied molecular orbitals of clusters, accepting electron from metal atoms at the interaction, than atoms of six-fold rings conjugated with other two mentioned types of rings

Clustering of Sc on SWNT and reduction of hydrogen uptake: Ab-initio all-electron calculations

Energies and kinetic barriers associated with transition metal (Sc) clustering on a single-walled carbon nanotube (SWNT) and graphene were studied by the all-electron density functional method. The analysis shows that the binding energy of Sc atom on SWNT is highly sensitive to the tube diameter and chirality. The metal atoms clustering on common SWNT, with diameters similar to 1-2 nm, is energetically favorable and kinetically permitted. Although well-separated, lone Sc atoms on SWNT can enhance the hydrogen storage capacity, their aggregation into clusters significantly reduces the hydrogen uptake; e.g., a Sc-4 cluster has the same hydrogen uptake as a single Sc atom. Our analysis shows that, although indeed light transition metal decorated SWNT present potential material for. the hydrogen storage, utter care should be taken to avoid the metal clustering on support material, to achieve and maintain higher hydrogen capacity