Effect Of Halogen Atoms Research Articles

Regulating effect of the halogen atoms on the cofacial dinuclear Schiff base complexes: Synthesis, spectroscopy, electrochemistry, and DFT calculations

The present study reports the synthesis and characterization of two new halogenated Schiff base copper (II) derivatives, namely [CuII2(3‐Cl‐Salmphen)2] (Cu‐Cl‐Salmphen) and [CuII2(3‐Br‐Salmphen)2] (Cu‐Br‐Salmphen), which were characterized by UV–Vis, FT‐IR, 1H‐NMR, and 13C‐NMR spectroscopy. Single crystal structural analysis revealed that each complex contains two crystallography independent, distorted copper centers, where each Cu center exhibits the same coordination environment with N2O2 donor atoms from two different ligands. To investigate the substitution effect of halogen atoms on the properties of the complexes, the non‐halogenated isomer [CuII2(H‐Salmphen)2] (Cu‐H‐Salmphen) was introduced for comparison. The differences between the halogenated and the non‐halogenated analogues were compared through spectroscopic, electrochemical, DFT, and TD‐DFT theoretical calculations. The optical experimental results indicated that the introduction of halogen atoms decreased the energy gap between the ground and excited states, leading to enhanced optical absorption capabilities of the compounds. Electrochemical tests showed that the halogenated analogues exhibited better electrochemical performance, and with the increase in an atomic number of the halogen atoms, the compounds displayed a gradual increase in cyclic voltammetry peak areas, diffusion coefficients, and conductivities. Theoretical calculations revealed that the introduction of halogen atoms simultaneously expanded the conjugated area of the molecules, decreased the HOMO‐LUMO energy levels of the complexes, and strengthened the intramolecular interactions. Furthermore, the potential mechanism of the tuning effect of halogen atoms on the charge transfer process was proposed.

Binary all-polymer solar cells with efficiency over 17% by fine-tuning halogenated thiophene linkers of polymer acceptors

All-polymer solar cells (APSCs) have achieved significant advances because of the rising of polymerized small molecular acceptors (PSMAs). While, the effect of halogen atoms on PSMAs in linkers has not been systematically studied. Herein, three PSMAs of PZC1, PZC2, and PZC3 are designed and synthesized by introducing fluorine and chlorine atom on the linkers to fine-tune their optoelectronic and molecular packing properties. Both halogenated polymer acceptors exhibit a slightly blue-shifted absorption range as well as deeper-lying frontier energy levels. When compared with non-halogenated PZC1, the fluorinated polymer acceptor (PZC2) presents better co-planar and rigid molecular conformation. The 3,4-dichlorothiophene-based polymer acceptor (PZC3) displays a distinctly twisted molecular chain between terminal groups and 3,4-dichlorothiophene owing to the steric hindrance between chlorine (Cl) and hydrogen (H) atoms. Due to the optimal morphologies in PM6:PZC2 film, the corresponding devices exhibit an excellent PCE of 17.30%, superior to those of PM6:PZC1 (13.83%) and PM6:PZC3 (15.75%) based devices. The mechanical robustness of three blend films is further investigated. PZC2-based films exhibit outstanding mechanical flexibility. Afterwards, the PM6:PZC2-based flexible devices achieve a PCE of 14.24%. Our results demonstrate that the usage of halogenated thiophene offers a practical way to fine-tune the performance of APSCs.

Halogen atom-doped graphene/MoSe2 heterojunction Schottky barrier height modulation

Achieving lower Schottky barrier heights in logic devices remains a formidable challenge. In this paper, the effect of halogen atoms doping on the type and height of graphene/MoSe2 Schottky is investigated using density functional theory. For monolayer MoSe2, the doping of halogen atoms introduces impurity energy levels in the energy band and leads to a change in the position of the Fermi energy level. Graphene and MoSe2 bonding retains their respective intrinsic electrochemical properties and bond with weak van der Waals forces to form n-type Schottky contacts. The doping of halogen atoms effectively changes the Schottky type and height of graphene/MoSe2. The Schottky type of heterojunctions doped with F, Cl, and Br atoms changes from n-type contacts to ohmic contacts. I and At atoms effectively reduce the Schottky barrier height of graphene/MoSe2. The disparity charge density indicates that the electrons in graphene are transferred to MoSe2, forming a built-in electric field pointing from graphene to MoSe2. After the doping of halogen atoms, the interlayer charge transfer between graphene and MoSe2 is significantly reduced, and the Fermi energy level appears to be shifted downward, which eventually leads to the reduction of the Schottky barrier height.

Monomeric octahedral bismuth(III) benzaldehyde-N1-alkyl thiosemicarbazones: Synthesis, characterization and biological properties

Due to their chemical and biological properties, the interest in thiosemicarbazones and their metal complexes is increasing day by day. In this study, the effect of the substituents at the N1 atoms of the thiosemicarbazones and the effect of halogen atoms on the type and biological properties of bismuth(III) complexes is investigated. The reactions of bismuth(III) halide with a series of benzaldehyde-N1-alkyl-thiosemicarbazones in 1:3 M ratio yield bismuth(III) halide complexes: {BiBr3(η1-S-Hbztsc)3} (1), {BiCl3(η1-S-Hbzmtsc)3} (2), {BiBr3(η1-S-Hbzmtsc)3} (3), {[BiCl3(η1-S-Hbzetsc)3].CH3OH} (4) and {BiBr3(η1-S-Hbzetsc)3} (5). Complexes 1–5 were characterized by a number of different spectroscopic methods. The crystal structures of complexes 1–5 and the free ligand benzaldehyde-N-methyl-thiosemicarbazone were determined by X-ray diffraction. Complexes 1–5 were tested for their in vitro cytotoxic activity against human breast adenocarcinoma (MCF-7) cell line. Complexes 1–5 showed low cytotoxic activity. The antibacterial activities of 1–5 and their free ligands against four strains bacteria of Staphylococcus epidermidis, Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli have been examined. The results indicated that bismuth(III) complexes 1–5 are most active against E. coli and, among them, complex 4 exhibits the highest activity. Lipoxygenase (LOX) inhibitory activity of the bismuth(III) halide complexes 1–5 and the free ligands has been detected experimentally. The IC50 values indicate that bismuth(III) halide complexes 1–5 have a higher enzyme inhibition potential than free ligands and cisplatin.

Halogen atom effect of fluorinated tolanes on their luminescence characteristics

Modification of the halogen constituent in the fluorinated tolane moiety is an effective method for tailoring the functionality of the material.

Mononuclear aggregation-induced emission (AIE)-active gold(I)-isocyanide phosphors: Contrasting phosphorescent mechanochromisms and effect of halogen substitutions on room-temperature phosphorescence nature

Developing phosphors with long-lifetime (millisecond scale or even longer) solid state room temperature phosphorescence (RTP) feature has attracted considerable attention. However, to date, stimuli-responsive phosphors with RTP nature are still rare due to the absence of effective guidelines for the exploitation of luminophors synchronously possessing stimuli-responsive and RTP characteristics. In this work, a series of mononuclear gold(I) complexes are reported. All these complexes exhibit various solid-state RTP properties, and phosphor 1-Cl exhibits long-lived RTP behavior. The effect of halogen atoms on the RTP nature of these complexes is investigated in detail. Furthermore, the introduction of different types of halogen atoms can effectively regulate the phosphorescent mechanochromism phenomena of these gold(I)-containing complexes. In addition, these phosphors display typical aggregation-induced emission (AIE) effect except for phosphor 5-CCl, which lacks hydrogen-bonding interactions compared with the other four phosphors. This work will be very helpful to the development of mechanical-force-responsive AIE phosphors with lasting RTP.

Theoretical research on mercury-laden halogenated activated carbon adsorbent bonding nature

Halogenated activated carbon adsorbents exhibit superior mercury capture performance in the flue gas. Not only the fabrication of effective adsorbents, but the used adsorbents stability is also crucial. It is essentially determined by product bonding nature. Here, Density functional theory was employed to investigate spent halogenated activated carbon adsorbents bonding nature at the atomic level. Seven possible mercury-containing product molecular geometries and effects of halogen species (X = Cl/Br/I) were considered. Specifically, bond length value, and bond order of Hg-C, Hg-X and C-X bonds of interest were calculated to investigate product stability in the gaseous phase. It was found that mercury was attached on the carbonaceous surface with C-Hg Mayer bond order around 0.5 in product structures G and H, suggesting a weak interaction. In other possible product molecular geometries, C-Hg or X-Hg exhibited a single bond character. Moreover, effects of halogen atoms on X-Hg and C-X bond strength were discussed. Electron localization function (ELF) and Localized orbital locator (LOL) were utilized to determine electron high localization regions. Results indicated C-Hg and C-X on the carbonaceous surface are covalent bonds and formed X-Hg bonds are ionic bonds. Furthermore, atom composition in the localized molecular orbital was calculated via the Hirshfeld method. In summary, this study investigated the bonding nature of used halogenated activated carbon adsorbents. The results are beneficial for fabricating more environmental-friendly mercury removal adsorbents in the future.

Studying the Effect of Halogen Atoms and the Cyano Groups on Optical, Electronic and Charge Transfer Properties of Hexasene Molecule: Molecular Design Methods, Structure-Property Relationship

Bu çalışmada, π-konjugasyon yapısına sahip hekzasen molekülü, farklı halojen atomlar (Flor, Klor, Brom) ve molekülde farklı konumlandırılmış siyano grupları ile dizayn edilmiş, elektronik, optik ve yük transfer özellikleri zamana bağlı ve zamandan bağımsız Yoğunluk Fonksiyon Teorisi (YFT) ile incelenmiştir. Dizayn edilen beş hekzasen türevinin yapı ve özellik arasındaki ilişkiyi kurabilmek için, moleküler geometri, reorganizasyon enerji, HOMO-LUMO orbital enerjileri, iyonizasyon potansiyeli (IP), elektron afinitesi (EA), geometriden dolayı nötr ve yüklü durumlara bağlı olarak bağ uzunluğu değişimi (BUD) üzerine substitüe etkisi incelenmiş ve etkiyi daha iyi anlayabilmek için sonuçlar hekzasen ve antrasen moleküllerin sonuçlarıyla karşılaştırılmıştır. Moleküllerin, elektron enjeksiyon bariyerinin hekzasen molekülünden daha düşük olduğu ve iyi bir boşluk taşıyıcısı olarak bilinen antrasenle kıyaslanabilir derecede etkili boşluk yük transfer oranına sahip olduğu belirtilmiştir. Dizayn edilen hekzasen türevlerinin, optoelektronik alanda potansiyel uygulamalar için ilgi çekebileceğini ve malzeme biliminde umut vaad edeceğini umuyorum.

The effect of halogen on arylsulfonylated phenothiazines for solid-sate luminescence and photocatalytic performance

Halogen atom effect on organic luminescence materials incorporating arylsulfonylated phenothiazine as the central unit was investigated in both solid state and organic solution. New organic solids with very weak C-halogen⋯π interactions are constructed, in which the packing style totally avoids the face-to-face stacking. Consequently, a high solid luminescent efficiency (81.37%) is obtained from a fluorine-substituted organic molecule crystal. The halogen atom effect on photocatalytic reaction was evaluated using arylsulfonylated phenothiazines, which catalyzed dehydrogenative coupling of amines to imines by simple blue light irradiation of the acetonitrile solution under aerobic atmosphere. The chlorine- substituted photocatalyst exhibited a higher reactivity than other ones, providing a preliminary insight for rational photocatalysts modification.

The effect of halogen atoms at propanoate anion on thermo physical, vibrational spectroscopy, chemical reactivity, biological properties of morpholinium propionate Ionic Liquid

The morpholinium cation based ionic liquids are designed to evaluate the thermophysical, chemical reactivity, and biological activity. To estimate and design the bioactive ILs, propionate and trihalopropanoate were considered under theoretical study by Density Functional Theory (DFT). To make effect of halogens atom on anion, propionate, trifluro propionate, trichloro propionate, and tribromo propionate were taken for optimization. Some thermodynamic and thermophysical properties such as free energy, entropy, dipole moment, binding energy, nuclear energy, electronics energy, and heat of formation were calculated using DFT method and make a comparative effect for halogen atoms activity on anion. The free energy, binding energy, and heat of formation were the highest on morphonium trifluro propionate (IL02) and the second is on tribromo propionate (IL04). Quantitative Structure Activity Relationship (QSAR) like charge density, surface area grid, volume, LogP, polarizability, refractivity, and molecular mass were simulated and recorded, from which the biological activity was calculated. The chemical reactivity like HOMO, LUMO, HOMO-LUMO gap, ionization potential, hardness, softness electronegativity and electron affinity were calculated. The vibrational spectroscopy and UV spectroscopy data provide them the identification and characterization. To sum up, the thermophysical properties are highly affected by trifluro propionate anion then tribromo propionate, trichloro propionate, and propionate respectively. On the other hand, the chemical reactivity increases in order IL04, IL03, IL02, IL01 but biological activity is inversely changed.

Cyclotriphosphazene-BODIPY Dyads: Synthesis, halogen atom effect on the photophysical and singlet oxygen generation properties

Two new dendrimeric cyclotriphosphazenes (CBD 1 and CBD 2) bearing six BODIPY units functionalized with halogens were successfully designed and synthesized. Their photophysical properties including absorption and emission profiles, fluorescence quantum yield, and fluorescence lifetime were investigated. The dendrimeric cyclotriphosphazene-BODIPY systems displayed intense absorption bands at about 530 nm with good molar extinction coefficients and weak emissions owing to the presence of halogen atoms in the structures. We also determined the singlet oxygen (1O2) formation abilities of the dendrimeric systems by chemical trapping and NIR phosphorescence methods. It was observed that the iodinated-BODIPY-cyclotriphosphazene dyad (CBD 1) was more efficient at generating 1O2 than that of the brominated-dyad (CBD 2). Besides, both dendrimeric systems showed more remarkable photosensitization ability than some commonly used photosensitizer based on porphyrin and BODIPY derivatives.

Effect of lateral substitution by chlorine and fluorine atoms of 4-alkyl-p-terphenyls on mesomorphic behaviour

The effect of halogen substitution on thermotropic liquid crystalline materials has a significant impact on many physical and chemical properties. Replacement of hydrogen atom by one of halogen can change and tune many important parameters such as dielectric anisotropy, viscosity, clearing and melting points, type and range of liquid crystalline phase and many others. Steric effect of halogen atoms and their polarity are two of the most important parameters, which have significant input to liquid crystalline properties. This work shows the correlation between the position of small size polar substituents (chlorine and fluorine atoms), their number and length of terminal alkyl chains (where alkyl chains are from ethyl to pentyl) on mesomorphic properties of twelve homologous series of terphenyl derivatives. Correlations for investigated compounds are supported by computational analysis of molecular polarizabilities, torsion angles between benzene rings and dipole moments. This work may be helpful for planning new structures of liquid crystalline compounds with predicted mesomorphism. Synthesized compounds show a strong tendency to form highly ordered smectic phases, while nematic phase is observed only for eleven compounds.

Structural, elastic, electronic, andoptical properties of layered TiNX (X = F, Cl, Br, I) compounds: a density functional theory study

ABSTRACTTitanium nitride halides, TiNX (X = F, Cl, Br, I) in the α-phase (orthorhombic) are exciting quasi two-dimensional (2D) electronic systems exhibiting a fascinating series of electronic ground states. Pristine TiNX are semiconductors with varying energy gaps and possess attractive properties for potential applications in optoelectronics, photovoltaics, and thermoelectrics. Alkali metal intercalated TiNCl becomes superconducting at reasonably high temperature. We have revisited the electronic band structure of TiNX using density functional theory (DFT) based calculations. The atomic orbital resolved partial electronic energy densities of states are calculated together with the total density of states (TDOS). The structural and elastic properties have been investigated in details for the first time. The elastic anisotropy has been explored. The optical properties of TiNX are studied for the first time. The Debye temperatures have been calculated and the related thermal and phonon parameters are discussed. The calculated physical parameters are compared with existing theoretical and experimental results and showed fair agreement. TiNX are found to reflect electromagnetic radiation strongly in the mid ultraviolet region. The elastic properties show high degree of anisotropy. The effect of halogen atoms on various structural, elastic, electronic, and thermal properties in TiNX are also discussed in detail.

A rational comparison of the effects of halogen atoms incorporated into the polymer donors on the performance of polymer solar cells

Despite the high performance polymer solar cells obtained by the fluorinated or chlorinated polymer donors, there is no effective guideline for how to choose a reasonable halogen atom incorporated into copolymer donors when designing organic photovoltaic materials. Two polymers of PBDT-F-3T2C containing F atom and PBDT-Cl-3T2C containing Cl atom are designed and synthesized. A direct comparison of the effects of fluorine and chlorine atom on the properties of the copolymer and resulting device performance is systematically studied. It can be found that both of the chlorine and fluorine atoms can effectively reduce the HOMO and LUMO levels, but chlorine atom is revealed to possess stronger downshifting ability for energy levels than fluorine atom in the copolymers. On the other hand, compared with the chlorine atom with larger atomic radius, the smaller fluorine atom possess strong self-assembly feature and negligible steric hindrance, enable the PBDT-F-3T2C with higher crystallinity and solution temperature-dependent aggregation behavior than PBDT-Cl-3T2C. The higher absorption coefficient, more favorable morphology, higher and more balanced charge mobilies endow the PBDT-F-3T2C with higher device performance than PBDT-Cl-3T2C (11.67% vs 10.19%). In addition, the performance of the 1,2,4-trimethylbenzene (TMB) solvent processed devices is also sensitive to halogenate atoms. An expressive PCE of 10.04% is obtained for F-containing devices, which is almost double higher than the Cl-containing devices. These results would provide a guideline for rational incorporation of halogen atoms into the polymer donors for high performance polymer solar cells. • Two polymer donors of PBDT-F-3T2C and PBDT-Cl-3T2C are designed and synthesized. • The effects of F and Cl atom on the properties of the polymers and PSCs. • A PCE of 11.67% obtained for halogenated solvent processed device. • Non-halogenated solvent processed devices yield a PCE over 10%.

Theoretical study on the substituent effect of halogen atom at different position of 7-azaindole-water derivatives: relative stability and excited-state proton-transfer mechanism

We have theoretically investigated the substituted effect on the first excited-state proton-transfer process of nX7AI-H2O (n = 2~6, X = F, Cl, Br) complex at the TD-M06-2X/6-31 + G(d, p) level. Here X is the substituted halogen atom, and n value denotes the substituted position of X, such as C2, C3, C4, C5, or C6. For the substituted 7-azaindole clusters, 6X7AI-H2O molecule is the most stable structure in water. The replacement of halogen atom X does not affect the characters of the HOMO and LUMO, but influence the S0 → S1 adiabatic transition energies of nX7AI-H2O (n = 2~6, X = F, Cl, Br). Our calculated results show that the double proton transfer occurs in a concerted but asynchronous protolysis pathway no matter which H atom is replaced by halogen atom. The halogen substitution changes the structural parameters evidently and leads to amply the asynchronousity during the proton-transfer process. The ESPT barrier height increases or decreases due to the halogen atom and substituted position.

Synthesis, Characterization and DFT Study of 4,4′-Oxydianiline Imines as Precursors of Tetrahalo-1,3-oxazepine-1,5-dione

This work presents four Schiff bases derived from 4,4′-Oxydianiline, distinguished by the para substituted halogen of benzaldehyde. These bases were used to synthesize eight compounds of di-1,3-oxazepine by direct condensation with tetrachloro phthalic anhydride and tetrabromo phthalic anhydride. The reactions were monitored with TLC and all structures were characterized using spectroscopic techniques such as FT-IR, 1H-NMR, 13C-NMR and C, H, N techniques. On the other hand, a theoretical study by Density Functional Theory (DFT) for the electronic structures was intended to study the effects of para-substituted halogen of benzaldehyde on the electronic structure of synthesized Schiff bases by using the Gaussian program. Theoretical results indicate that there is no effect of halogen atoms except for bromine on HOMO and LUMO energies of the synthesized compounds.

Halogen atom effect on the photophysical properties of substituted aza-BODIPY derivatives.

The influence of halogen atom substitution (Br and I), in different amounts and positions in an aza-BODIPY skeleton, on the photophysical properties of some aza-BODIPY derivatives has been investigated by using density functional theory and its time-dependent extension. The heavy atom effect on excitation energies, singlet-triplet energy gaps and spin-orbit matrix elements has been considered. The maximum absorption within the therapeutic window has been confirmed for all the aza-BODIPY derivatives. The feasible intersystem spin crossing pathways for the population of the lowest triplet state, that will depend on the values of the spin-orbit matrix elements, the energy gap as well as the orbital composition of the involved states have been found to most likely involve the S1 and T1 or T2 states. The outcomes of computations support the potential therapeutic use of these compounds as photosensitizers in photodynamic therapy.

Theoretical Investigation on the Substituent Effect of Halogen Atoms at the C8 Position of Adenine: Relative Stability, Vibrational Frequencies, and Raman Spectra of Tautomers.

We have theoretically investigated the substituent effect of adenine at the C8 position with a substituent X = H, F, Cl, and Br by using the density functional theory (DFT) at the B3LYP/6-311+G(d, p) level. The aim is to study the substituent effect of halogen atoms on the relative stability, vibrational frequencies, and solvation effect of tautomers. Our calculated results show that for substituted adenine molecules the N9H8X tautomer to be the most stable structure in gas phase at the present theoretical level. Here N9H8X denotes the hydrogen atom binds to the N9 position of imidazole ring and X denotes H, F, Cl, and Br atoms. The influence of the induced attraction of the fluorine substituent is significantly larger than chlorine and bromine ones. The halogen substituent effect has a significant influence on changes of vibrational frequencies and Raman intensities.

Halogen atom effect on the magnetic anisotropy of pseudotetrahedral Co(II) complexes with a quinoline ligand

Triclinic and monoclinic polymorph modifications of the complex [Co(qu)2Br2] were obtained, and its molecular and crystal structures were determined by single crystal X-ray analysis. The magnetic anisotropy parameter D and g-tensor were estimated by SQUID measurements and ab initio (SA-CASSCF/NEVPT2) quantum-chemical calculations. The ligand field effect and magnetostructural correlations in the family of complexes [Co(qu)2X2] (qu=quinoline and X=NCS−, Cl−, Br− and I−) were analyzed. A correlation between the ligand field and the energies of the molecule excited states was revealed.

First hyperpolarizability of Ru-half-sandwich complexes: The effect of halogen atom substitution on the ancillary ligand

The first hyperpolarizability (β) of a series of half-sandwich Ru complexes with a mercaptobenzothiazole ligand bearing a halogen atom substitution in the para-position has been investigated by hyper-Rayleigh scattering and quantum chemical calculations. The heterocyclic ligand with a bromine atom in the para position makes it a very good donor and charge flows to the Ru center enhancing the β value of the complex by a factor of 2 compared to the complex with the ligand without the halogen substitution. The resonance (+R) and the inductive (-I) effects exerted by the halogen atom in the para position push electrons in opposing directions in the complex. For the Br and Cl atoms the resonance effect dominates which enables the ligand to donate electrons to the metal center thereby increasing the hyperpolarizability whereas for the fluorine atom, the inductive effect is dominant which reduces the charge flow to the metal and the hyperpolarizability drops even below that of the unsubstituted ligand. This unprecedented halogen atom effect on β of metal complexes is reported.