Naphthalene Molecules Research Articles

Catalytic polymerization of naphthalene by HF/BF3 super acid: an ab initio density functional theory study.

Mesophase pitch fabricated through polymerization of polycyclic aromatic hydrocarbons (PAHs) is highly aromatic and of high quality, and it can be used as a raw material to produce other carbon-based materials. Hydrofluoride/boron trifluoride (HF/BF3) is currently an efficient reagent to catalyze the PAH polymerization to produce mesophase pitch. In this study, density functional theory (DFT) calculations are performed to propose a mechanism for naphthalene catalytic polymerization using HF/BF3. The overall reaction mechanism can be conceptualized as having two stages: activation, followed by polymerization. During activation, HF/BF3 acts a proton donor to activate naphthalene, whose then-protonated form can promote the formation of a C-C bond with another naphthalene molecule via electrophilic addition. We also propose a catalyst recovery pathway, which can stabilize the intermediate products. In the polymerization stage, two types of pathways are proposed, those of chain elongation and intramolecular cyclization. According to the proposed catalytic mechanism in this study, the predicted mesophase product shows highly aliphatic hydrogens, which is consistent with the experimental results. We propose the full catalytic mechanism using DFT calculations. Our results provide a better understanding of how to develop novel and green catalysts, which can replace the HF/BF3 reagent in future applications.

Computer Simulation Studies of Structure Characteristics of Ordered Mesoporous Carbons and its Naphthalene Adsorption Performance

Through naphthalene-adsorption experiments, we were able to draw some valuable conclusions about adsorption capacity, the adsorption isotherm, adsorption kinetics, and adsorption thermodynamics, although the experiments could not directly reveal the exact location and state of adsorption on the surface of ordered mesoporous carbons (OMCs). In fact, due to the restrictions of characterization technology, human factors, and experimental conditions, we still do not understand the microscopic structure of OMCs very well. However, molecular simulation technology could compensate for these disadvantages. In this study, the Grand Canonical Monte Carlo method has been used to simulate the naphthalene adsorption behavior in the OMC-structure model for the first time. The atomic structure model of OMCs was built firstly by using molecular modeling techniques and was characterized by calculating the accessible solvent surface area, total pore volume, and small-angle X-ray diffraction patterns. The calculated results showed that the structural model of OMCs was reasonable and that the structural characteristics were in agreement with experimental data. The adsorption isotherm curve is of the type Langmuir IV, which is a typical characteristic of ordered mesoporous materials. Also, the adsorption isotherm curve revealed that the adsorption capacity of naphthalene on OMCs gradually increased to a balance, with the maximum capacity reaching 105.4 mg g–1. Additionally, as the number of naphthalene molecules increased, the adsorption state was observed progressing from a monolayer to a multilayer state in the mesopores. This work deepened the understanding of the adsorption state of naphthalene for OMCs on the mesoscopic level. It also demonstrated that the GCMC method is effective for studying the adsorption process and gives useful guidance on research of the structure-activity relationship and performance prediction of carbon material.

Hybrid image potential states in molecular overlayers on graphene

The structural and electronic properties of naphthalene adsorbed on graphene are studied from first principles using the van der Waals density functional method. It is shown that naphthalene molecules are stabilized by forming a superstructure with the periodicity of $(2\sqrt{3}\ifmmode\times\else\texttimes\fi{}2\sqrt{3})$ and a tilted molecular adsorption geometry on graphene, in good agreement with the scanning tunneling microscopy (STM) experiments on highly oriented pyrolytic graphite. Our results predict that image potential states (IPSs) are induced by intermolecular interaction on the naphthalene overlayer, hybridizing with the IPSs derived from graphene. The resultant hybrid IPSs are characterized by anisotropic effective mass reflecting the molecular structure of naphthalene. By means of STM simulations, we reveal that one of the hybrid IPSs manifests itself as an oval protrusion distinguishable from naphthalene molecular orbitals, which identifies the origin of an experimental STM image previously attributed to the lowest unoccupied molecular orbital of naphthalene.

Molecularly imprinted polymer membrane for the removal of naphthalene from petrochemical wastewater streams

AbstractThe aim of this work was the preparation of molecularly imprinted membrane (MiM) using polysulfone (PSf) polymer for targeted removal of polycyclic aromatic hydrocarbons from petrochemical wastewater. Naphthalene was opted as a model pollutant, and the imprinted membrane was fabricated by phase inversion technique. Nonimprinted membrane (NiM) was also prepared in the absence of naphthalene and used as a reference. The polymers (MiM/NiM) were systematically characterized using different characterization techniques. The selectivity property of the membranes was evaluated by their ability in separation of naphthalene through filtration tests. Results showed that in comparison with NiM, the imprinted membrane exhibits higher affinity toward naphthalene molecules. It was found that the selectively of MiM is 2.27‐fold more than that of the corresponding NiM. This finding can be encouraging from industrial applications points of view.

Competitive-Binding Activated Supramolecular Nanovalves Based on β-Cyclodextrin Complexes

Competitive binding activated nanovalves (CBAN) with on-demand activation capability are fabricated through switching from host-guest complexation to decomplexation upon the introduction of competitive guest (C-guest) molecules. Guest molecules of pyrene or naphthalene are used to associate with β-cyclodextrin (β-CD) host to form supramolecular complexes. These supramolecular conjugations were assembled on the surface of mesoporous silica nanoparticles (MSNs), which played a role of “nanovalve” for blocking the nanopores. For the activation of nanovalves, C-guest of 1-adamantanamine hydrochloride (Ad), was added to dissociate formerly assembled complex by competitive binding with host β-CD. In controlled release study, the fabricated CBAN was stable at “Off” state for preventing cargo release, and able to release the cargo efficiently at “On” state. Moreover, the competitive binding process was also investigated by using fluorescein isothiocyanate modified β-CD. It was found that the shift of host-guest complexation equilibrium by C-guest activates the CBAN. These results would shed lights on the development of novel supramolecular nanovalves.

Guest Induced Strong Cooperative One- and Two-Step Spin Transitions in Highly Porous Iron(II) Hofmann-Type Metal-Organic Frameworks.

The synthesis, crystal structure, magnetic, calorimetric, and Mössbauer studies of a series of new Hofmann-type spin crossover (SCO) metal-organic frameworks (MOFs) is reported. The new SCO-MOFs arise from self-assembly of FeII, bis(4-pyridyl)butadiyne (bpb), and [Ag(CN)2]- or [MII(CN)4]2- (MII = Ni, Pd). Interpenetration of four identical 3D networks with α-Po topology are obtained for {Fe(bpb)[AgI(CN)2]2} due to the length of the rod-like bismonodentate bpb and [Ag(CN)2]- ligands. The four networks are tightly packed and organized in two subsets orthogonally interpenetrated, while the networks in each subset display parallel interpenetration. This nonporous material undergoes a very incomplete SCO, which is rationalized from its intricate structure. In contrast, the single network Hofmann-type MOFs {Fe(bpb)[MII(CN)4]}·nGuest (MII = Ni, Pd) feature enhanced porosity and display complete one-step or two-step cooperative SCO behaviors when the pores are filled with two molecules of nitrobenzene or naphthalene that interact strongly with the pyridyl and cyano moieties of the bpb ligands via π-π stacking. The lack of these guest molecules favors stabilization of the high-spin state in the whole range of temperatures. However, application of hydrostatic pressure induces one- and two-step SCO.

The mechanism of the Bose–Einstein condensation and its role in the occurrence of the normal currents and supercurrents

The mechanism of the Bose–Einstein condensation and its role in the occurrence of the normal currents and supercurrents is investigated. In particular, the mechanism of the formation of Cooper pairs and their role in the occurrence of non dissipative diamagnetic supercurrents is investigated. In the previous works [1–7], we suggested that in the materials with large HOMO-LUMO gaps, t he Cooper pairs are formed by the large HOMO-LUMO gaps as a consequence of the quantization of the orbitals by nature, and by the attractive Coulomb interactions between two electrons with opposite momentum and spins occupying the same orbitals via the positively charged nuclei. On the other hand, according to the recent experimental research (Wehlitz et. al; 2012), the Cooper pairs have been observed at room temperatures in the neutral benzene (6an), naphthalene (10ac), anthracene (14ac), and coronene molecules. That is, our prediction in our theoretical researches [1–7] can be well confirmed by the recent experimental research (Wehlitz et. al; 2012), and our previous theory can be reasonably applied to the explanation of the mechanism of the occurrence of the granular high temperature superconductivity in carbon materials. Related to seeking for the room-temperature superconductivity, in this article, we compare the normal metallic states with the superconducting states. Furthermore, in this article, we elucidate the mechanism of the Ampere’s law (experimental rule discovered in 1826) in normal metallic and superconducting states, on the basis of the theory suggested in our previous researches. Article DOI: http://dx.doi.org/10.20319/mijst.2015.11.5882 This work is licensed under the Creative Commons Attribution-Non-commercial 4.0 International License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc/4.0/ or send a letter to Creative Commons, PO Box 1866, Mountain View, CA 94042, USA.

Synthesis of graphene from naphthalene molecules on the surface of a Langmuir monolayer

This paper considers some approaches to the technology of the synthesis of a graphene monolayer at a phase interface. A surfactant monolayer on an aqueous subphase is proposed as the substrate for graphene synthesis. A monolayer is formed by the Langmuir–Blodgett method. Simple polyaromatic molecules, in particular, naphthalene, are considered as the basic substance for the synthesis of graphene. Arachidic acid is used as the basic surfactant molecule. To confirm the possibility of synthesizing graphene by the mentioned method, both experimental and theoretical studies are performed. In the course of experiemnts, it is shown that naphthalene molecules are pressed into the space above arachidic acid molecules upon the compression of monolayer of arachidic acid–naphthalene mixtures (such an assumption is made due to the characteristic value of the surface areas attributed to different phases of the monolayer and also to its characteristic parameters). The formation of a layer of naphthalene molecules on the surface of a monolayer is modeled by the molecular dynamics method (Amber potential). Different variants of the initial distribution of molecules are considered.

Stability and molecular properties of the boron-nitrogen alternating analogs of azulene and naphthalene: a computational study.

In this work, the spectroscopic information, stability and aromaticity of the boron-nitrogen azulene and naphthalene molecules are provided by the use of CC2 (geometry optimization, dipole moment, UV-vis spectrum calculations) and DFT (vibrational spectrum and NMR calculations) methodologies. One isomer of the investigated boron-nitrogen naphthalene (boroazanaphthalene) and two isomers of boron-nitrogen azulene, 1,3,4,6,8-pentaaza-2,3a,5,7,8a-pentaboraazulene (BN-azulene) and 2,3a,5,7,8a-pentaaza-1,3,4,6,8- pentaboraazulene (NB-azulene), are stable systems. However, these molecules have different properties, i.e., different stability, dipole moment, and aromaticity based on the NICS approach. BN-naphthalene has a high dipole moment magnitude showing high polar character, while naphthalene is apolar. BN- and NB-azulene are weakly polar, while ordinary azulene is highly polar in character. Also, substitution of C atoms by B and N atoms decreases the aromaticity. In the case of NB-azulene, the seven-membered ring has anti-aromaticity behavior while both rings of BN-azulene exhibit aromaticity. We expect that the new theoretical data provided in this work will be useful in identifying and characterizing experimentally the compounds investigated, and in helping our understanding of the chemistry of boron-nitrogen molecules. Graphical abstract Boron-nitrogen alternating analogs of azulene. Spectral distinction between isomers.

Naphthalene condensation as a means of producing nanostructured graphene

Abstract The study provided the results of simulations (molecular modeling and quantum chemical) and physicochemical studies of a potential method of graphene sheet formation using the surface of water or water-surfactant monolayer as a substrate (base) and naphthalene as an initial compound. According to molecular dynamics simulation, arachic acid is a viable choice for a substrate as naphthalene molecules are unable to penetrate it and remain on its surface. The results of simulation have been confirmed by surface tension studies via Langmuir-Blodgett method. The potential of several compounds (namely, Pt, Pd, Ni, AlCl3 and PdCl4) as catalysts for naphthalene condensation has been estimated by semiempirical and DFT calculations. According to calculation results, Ni and Pd may be the most efficient catalysts for this reaction.

Growth and Destruction of PAH Molecules in Reactions with Carbon Atoms

Abstract A very high abundance of atomic carbon in the interstellar medium (ISM), and the high reactivity of these species toward different hydrocarbon molecules including benzene, raise questions regarding the stability of polycyclic aromatic hydrocarbon (PAH) molecules in space. To test the efficiency of destruction of PAH molecules via reactions with atomic carbon, we performed a set of laboratory and computational studies of the reactions of naphthalene, anthracene, and coronene molecules with carbon atoms in the ground state. The reactions were investigated in liquid helium droplets at T = 0.37 K and by quantum chemical computations. Our studies suggest that all small and all large catacondensed PAHs react barrierlessly with atomic carbon, and therefore should be efficiently destroyed by such reactions in a broad temperature range. At the same time, large compact pericondensed PAHs should be more inert toward such a reaction. In addition, taking into account their higher photostability, much higher abundances of pericondensed PAHs should be expected in various astrophysical environments. The barrierless reactions between carbon atoms and small PAHs also suggest that, in the ISM, these reactions could lead to the bottom-up formation of PAH molecules.

Crossover from localized to itinerant states in hydrocarbon Mott insulators.

Crossover from an itinerant state to an isolated electronic state in electron-doped polycyclic aromatic hydrocarbon (PAH) was studied for the two smallest zigzag-type molecules of naphthalene (NN) and anthracene (AN) by focusing on their 1 : 1 stoichiometry, A1(NN) and A1(AN), with alkali metals (A = K and Rb). The competition between on-site Coulombic repulsion energy (U) and bandwidth (W) was argued in terms of their magnetic and electrical properties upon lattice expansion, when A varies from K, with a smaller ionic radius, to Rb, with a larger ionic radius. The temperature-dependence of magnetic susceptibility shows a pronounced hump associated with antiferromagnetic (AFM) interactions for Rb1(NN), being similar to those of K1(NN) and K1(AN) in the earlier report. On the other hand, Rb1(AN) intriguingly exhibits paramagnetic susceptibility, observed in a nearly localized electron system, being apart from an highly correlated Mott insulating state. Crystal structural analyses of the X-ray diffraction profiles show a small difference in lattice parameters of the ab plane among K1(NN), K1(AN), and Rb1(NN), whereas Rb1(AN) exhibits a significantly larger value than those of the others, being indicative of greatly modified interaction energies. The different magnetic properties observed in Rb1(AN) are interpreted from its modified intermolecular distance. The possibility of an emergent metallic state of K1(AN) under high pressure has also been described, referring to electrical transport measured under high pressure.

Matrix effects in the C 1s photoabsorption spectra of condensed naphthalene.

High-resolution C 1s near-edge x-ray absorption fine structure (NEXAFS) spectra of naphthalene are investigated. By comparing the spectral signatures of condensed naphthalene molecules with those of naphthalene in the gas phase, we are able to unambiguously identify spectral features which are affected by the intermolecular interactions in the condensed phase. With the help of calculations using time-dependent density-functional theory and the second-order algebraic-diagrammatic construction scheme for the polarization propagator, resonances in the relevant energy range can be assigned to valence and Rydberg-like excitations. Thus, we obtain a more detailed identification of NEXAFS resonances beyond the present literature.

Computer simulation of a phosphorescent probe inside [formula omitted]-cyclodextrin matrices

Molecular dynamics simulations of the different self-assembled structures based on the β-cyclodextrin and adamantane were performed. The line shift and non-uniform broadening of the T1→S0 transition of naphthalene molecule inserted into these structures were calculated. It was found that line width is mainly governed by the nearest-neighbor environment. The most important factor was the existence of the typical “sandwich” structural pattern. The main findings provide a way to the rational design of new materials for nanophotonics.

A theoretical study of charge transport properties of trifluoromethyl (-CF3) substituted naphthalene (TFMNA) molecule

We present a density functional (DFT) study of the charge transport properties of CF3-naphthalene. Nature of charge transport is investigated using parameters such as reorganization energy (X), transfer integral (t), ionization potential (IP), electron affinity (EA), and carrier mobility (μ) computed through electronic structure calculations. We observe a decrease in X and IP from 2,6-DTFMNA to 1,5-DTFMNA, whereas, the EA is found to be enhanced, as a result p-type characteristics, with mild n-type signature, in the organic semiconductor gets increased. In addition, the HOMO-LUMO gap also gets reduced inferring more charge injection through the potential barrier. The maximum hole and electron mobility values for the substituted compound are obtained to be 2.17 cm2/ Vsec & 0.20 cm2/ Vsec, respectively.

Artificial Force Induced Reaction (AFIR) Method for Exploring Quantum Chemical Potential Energy Surfaces.

In this account, a technical overview of the artificial force induced reaction (AFIR) method is presented. The AFIR method is one of the automated reaction-path search methods developed by the authors, and has been applied extensively to a variety of chemical reactions, such as organocatalysis, organometallic catalysis, and photoreactions. There are two modes in the AFIR method, i.e., a multicomponent mode and a single-component mode. The former has been applied to bimolecular and multicomponent reactions and the latter to unimolecular isomerization and dissociation reactions. Five numerical examples are presented for an Aldol reaction, a Claisen rearrangement, a Co-catalyzed hydroformylation, a fullerene structure search, and a nonradiative decay path search in an electronically excited naphthalene molecule. Finally, possible applications of the AFIR method are discussed.

Entanglement entropy of electronic excitations.

A new perspective into correlation effects in electronically excited states is provided through quantum information theory. The entanglement between the electron and hole quasiparticles is examined, and it is shown that the related entanglement entropy can be computed from the eigenvalue spectrum of the well-known natural transition orbital (NTO) decomposition. Non-vanishing entanglement is obtained whenever more than one NTO pair is involved, i.e., in the case of a multiconfigurational or collective excitation. An important implication is that in the case of entanglement it is not possible to gain a complete description of the state character from the orbitals alone, but more specific analysis methods are required to decode the mutual information between the electron and hole. Moreover, the newly introduced number of entangled states is an important property by itself giving information about excitonic structure. The utility of the formalism is illustrated in the cases of the excited states of two interacting ethylene molecules, the conjugated polymer para-phenylene vinylene, and the naphthalene molecule.

Computational Evidence of Inversion of (1)La and (1)Lb-Derived Excited States in Naphthalene Excimer Formation from ab Initio Multireference Theory with Large Active Space: DMRG-CASPT2 Study.

The naphthalene molecule has two important lowest-lying singlet excited states, denoted (1)La and (1)Lb. Association of the excited and ground state monomers yields a metastable excited dimer (excimer), which emits characteristic fluorescence. Here, we report a first computational result based on ab initio theory to corroborate that the naphthalene excimer fluorescence is (1)La parentage, resulting from inversion of (1)La and (1)Lb-derived dimer states. This inversion was hypothesized by earlier experimental studies; however, it has not been confirmed rigorously. In this study, the advanced multireference (MR) theory based on the density matrix renormalization group that enables using unprecedented large-size active space for describing significant electron correlation effects is used to provide accurate potential energy curves (PECs) of the excited states. The results evidenced the inversion of the PECs and accurately predicted transition energies for excimer fluorescence and monomer absorption. Traditional MR calculations with smaller active spaces and single-reference theory calculations exhibit serious inconsistencies with experimental observations.

Encapsulating Naphthalene in an Electron-Deficient MOF to Enhance Fluorescence for Organic Amines Sensing.

Host-guest encapsulation of electron-rich naphthalene molecules into a weakly emissive porous metal-organic framework based on π-electron-deficient (π-acidic) naphthalene diimide tectons leads to orange-emissive crystals, which can be used to sense strongly basic organic amines in a fast response, high photostability, and tunable sensitivity. Moreover, such host-guest inclusion crystals are also a good photochromic probe for the detection of weakly basic N-methyl-2-pyrrolidone and N,N-dimethylformamide molecules.

Unusual Fragmentation and Transformation of an N-Heterocyclic Carbene by a Stable Phosphonium-Borane peri-Functionalized Naphthalene.

A 1-phosphonium-8-borane-decorated naphthalene molecule 2 has been found to react with N,N'-dimethylimidazol-2-ylidene (IMe), a popular member of the N-heterocyclic carbene (NHC) family, which converts it into two vinyl-amine fragments one of which is trapped between the phosphonium and borane unit by the formation of a C-C and a B-N bond. The same reactivity was not observed for larger NHC molecules. Control experiments and mechanistic studies have established the involvement of an ylide-borane molecule and an imidazolium salt in addition to IMe carbene in this new transformation of an NHC.