Electron-acceptor Substituents Research Articles

General synthetic method for NH-indoles starting from N-hydroxyindoles

A general and efficient method has been developed for the synthesis of NH-indoles bearing electron-accepting substituents via the modification of corresponding N-hydroxyindoles.

Surface chemistry of 2,3-dibromosubstituted norbornadiene/quadricyclane as molecular solar thermal energy storage system on Ni(111).

Dwindling fossil fuels force humanity to search for new energy production routes. Besides energy generation, its storage is a crucial aspect. One promising approach is to store energy from the sun chemically in strained organic molecules, so-called molecular solar thermal (MOST) systems, which can release the stored energy catalytically. A prototypical MOST system is norbornadiene/quadricyclane (NBD/QC) whose energy release and surface chemistry need to be understood. Besides important key parameters such as molecular weight, endergonic reaction profiles, and sufficient quantum yields, the position of the absorption onset of NBD is crucial to cover preferably a large range of sunlight's spectrum. For this purpose, one typically derivatizes NBD with electron-donating and/or electron-accepting substituents. To keep the model system simple enough to be investigated with photoemission techniques, we introduced bromine atoms at the 2,3-position of both compounds. We study the adsorption behavior, energy release, and surface chemistry on Ni(111) using high-resolution X-ray photoelectron spectroscopy (HR-XPS), UV photoelectron spectroscopy, and density functional theory calculations. Both Br2-NBD and Br2-QC partially dissociate on the surface at ∼120 K, with Br2-QC being more stable. Several stable adsorption geometries for intact and dissociated species were calculated, and the most stable structures are determined for both molecules. By temperature-programmed HR-XPS, we were able to observe the conversion of Br2-QC to Br2-NBD in situ at 170 K. The decomposition of Br2-NBD starts at 190 K when C-Br bond cleavage occurs and benzene and methylidene are formed. For Br2-QC, the cleavage already occurs at 130 K when cycloreversion to Br2-NBD sets in.

Facile color tuning of thermally activated delayed fluorescence by substituted ortho-carbazole-appended triarylboron emitters

We report the facile tuning of the emission color of thermally activated delayed fluorescence (TADF) emitters based on an ortho-carbazole-appended triarylboron. A series of ortho-carbazole-appended triarylboron compounds (2–7) are prepared by introducing various electron-accepting substituents, such as phenyl, pyridyl, pyrimidyl, diphenylphosphine oxide, cyano, and dimesitylboryl groups, to the phenylene ring of the dimesitylphenylboryl (PhBMes2) acceptor moiety in the parent ortho-carbazole-appended triarylboron (CzoB, 1). The X-ray crystal structure of the cyano-substituted compound 6 confirms the twisted connectivity between the Cz and phenylene rings. All the compounds exhibit strong TADF (ΦPL = 48–93% in toluene) with large delayed portions. In particular, the emission bands gradually undergo bathochromic shifts from blue (λPL = 463 nm for 1) to greenish yellow (λPL = 532 nm for 7) depending on the electron-accepting substituents. Electrochemical studies show that the greater stabilization of the LUMO level compared to the HOMO is responsible for the red shifts of the emission. Theoretical studies further support the observed bathochromic shifts in the emission, as well as the small energy splittings (ΔEST) between the excited singlet and triplet states that afford the efficient TADF.

Synthesis of Pyrrole Derivatives Promoted by Fe(ClO4)3/SiO2 as an Environmentally Friendly Catalyst

N-Substituted pyrroles have been prepared in high isolated yields (702-99%) by the reaction of hexane-2,5-dione with amines or diamines in the presence of Fe(ClO4)3/SiO2 at ambient temperature under solvent-free conditions. The experimental procedure involves simple operations, and the products are readily separated by short column chromatography. The same reaction of hexane-2,5-dione with amines containing electron-acceptor substituents, such as 4-nitroaniline, resulted in fair yields of pyrrole derivatives.

Synthesis and Spectroscopic Characterisation of Some Novel Butadienyl Asycyanine Colorants having Lepidine Moiety

Twenty-one novel chromophoric chain β-substituted butadienyl asycyanine colorants have been synthesized by catalytic condensation of (i) dimethylaminostyryl phenyl ketone, (ii) 4ʹ-dimethylaminostyryl-4ʹ-nitrophenyl ketone and (iii) 4ʹ-dimethylaminostyryl-4ʹ-methoxyphenyl ketone with seven lepidinium methyliodide salts in ethanolic DMF medium using piperidine as basic catalyst. These colorants were synthesized with the objective to study the effect of electron acceptor and electron donor group substituent at 4ʹ-position in the chain β-phenyl nucleus on visible absorption maxima. The newly prepared colorants were found to exhibit uniform increase in absorption maxima i.e. Red shift (RS), when collated with analogues having no substituent in the β-phenyl nucleus. Again the absorption maxima of the title colorants were found to be higher than the absorption maxima of previously prepared butadienyl colorants having quinoline mioety of same conjugated system.

N-TROPYLATION OF ARYLAMINES

An efficient method for introduction of biogenic tropylium cycle into aromatic amines molecules is offered. Introduction is carried out in the presence of imidazole as a strong base. Interaction between tropylium salts (tetrafluoroborate or perchlorate) and aromatic amines with either nitro- or acetyl groups (meta-nitroaniline, para-nitroaniline, 2-methyl-4-nitroaniline and para-acetylaniline) as electron-acceptor substituents in the benzol ring results in stable products resulting from substitution of the hydrogen atom in the amino group of aromatic amines, namely: 4-nitro-N-(1'-cyclohepta-2',4',6'-trienil)aniline, 2-methyl-4-nitro-N-(1'-cyclohepta-2',4',6'-trienil)aniline, 3-nitro-N-(1'-cyclohepta-2',4',6'-trienil)aniline, 4-acetyl-N-(1'-cyclohepta-2',4',6'-trienil)aniline. The yields of the compounds obtained attain 60-87%. In this process, imidazole forms with the tropylium cation a complex which (1) serves as a carrier of tropylium ion to the nitrogen atom of aromatic amine, thus lightening the electrophilic substitution process at the hydrogen atom of the amino group; (2) prevents the dehydration process of resulting N-(1'-cyclohepta-2',4',6'-trienil) anilines. The latter phenomenon is an advantage in comparison with the method in which the dehydration process results in unstable N-aryl-8-azaheptafulvenes instead of stable N-tropylated anilines. The structure of the compounds obtained is confirmed by the method of mass spectrometry, NMR on protium nuclei and XRD analysis for 4-nitro-N-(1'-cyclohepta-2',4',6'-trienil)aniline. Antimicrobial activity is studied on conditionally pathogenic St. aureus 906, C. albicans ATCC 24433 and E. coli 1257 strains. The investigation results show all the synthesized compounds to exhibit antimicrobial activity. The compounds N-(3-nitrophenyl)cyclohepta-2,4,6-trienamine and N-(4-acylphenyl)cyclohepta-2,4,6-trienamine at concentration 125 microgram/ml are ascertained to exhibit inhibitory action on growth and development of the test strains, with this effect being less expressed for compounds N-(4-nitrophenyl)cyclohepta-2,4,6-trienamine and N-(2-methyl-4-nitrophenyl)cyclohepta-2,4,6-trienamine.

Synthesis of 2-methyl-5-(5-phenyl substituted-1,3,4 oxadiazole-2-yl) quinazolin-4-one fluorescent brightening agent: Computational and experimental comparison of photophysical structure

Report is about the synthesized new range of oxadiazole substituted quinazoline and studied its electronic distribution to attribute fluorescent properties. B3LYP Density Functional Theory (DFT) computational optimization was studied to observe the effect of electron donor and acceptor substituent's on photophysical properties, electronic state and energy level. DFT computational optimization was performed by Polarizable Continuum Model (PCM) of solvation strictly in the gas phase and DMF maintaining C1 symmetry in ground state geometry structure. UV–vis and fluorescence spectroscopic methods help in understanding the relationship between the electron donor and acceptor functional groups on the photophysical properties. Eventually comparing experimental spectral emission and DFT computations were envisage understanding the changes of the electronic transition, energy levels, and electronic orbital distribution in the substituted quinazoline structure. These compounds have good fluorescent brightening properties hence studied and applied as fluorescent brightening agent on polyester fiber.

ВЛИЯНИЕ ПРИРОДЫ ЗАМЕСТИТЕЛЯ В АЗОБЕНЗОЛЬНЫХ ХРОМОФОРАХ НА ДИФРАКЦИОННУЮ ЭФФЕКТИВНОСТЬ ПОЛЯРИЗАЦИОННЫХ ГОЛОГРАММ

The films of polymeric composites containing monomers of azobenzene dyes or azobenzene lateral groups chemically bonded to the main polymer chain demonstrate photoactive properties, and can be used in electrooptical light modulators and in recording media (RM) for polarization holography. Photoinduced optical anisotropy (PIA) appears under influence of linearly polarized light caused by the processes of trans-cis-izomerization of the azobenzene groups. This process is determining for application of the considered materials as RM for polarization holography. The films of polymeric polarization sensitive media based on a copolymer of styrene with nonyl methacrylate doped with azobenzene-type dyes with different electron-acceptor substituents are obtained in this work. In the films of copolymer the holograms of the plane wave front were registered for parallel and orthogonal orientations of polarization vectors of the object and reference light beams. Their photoelectrophysical, in particular photodielectric, and information properties are investigated. It was established, that when the mutual orientation of the recording beams changes from the orthogonal to parallel orientation the diffraction efficiency of the holograms increases in the case of using azo dye with the maximum number of auxochromic substituents in the molecule. The effect of the diffraction efficiency dependence on the chromophores structure is connected with the deepening of dye color. The photo-induced optical anisotropy in the films appears due to a change of the concentration ratio of trans- and cis-isomers of azobenzene dye fragments. This conclusion is confirmed by the photodielectric measurements data, namely, by the negative sign of the photodielectric effect, observed experimentally in the investigated thin film structures. It was shown, that investigated compositions can be used as information media for polarization holography.

New spirohydantoins derived from β-tetralone: Design, synthesis and evaluation of their pharmacokinetically relevant propertie

To create new anticonvulsant drugs, two series of spirohydantoins derived from ?-tetralone bearing a 4-substituted benzyl group (1a?1g) or a 2-(4-substituted phenyl)-2-oxoethyl group (2a?2f) in position 3 of the hydantoin ring were synthesized. The chemical structure of these compounds was confirmed by determination of the melting point, elemental analysis and FT-IR, 1H NMR, 13C NMR and UV-Vis spectroscopic methods. Effects of the substituents in the benzyl moiety on the shift of the absorption maxima of compounds 1a?1g and 2a?2f were analyzed using the Hammett's equation. Namely, a split in the Hammett plot at the parent compounds 1a and 2a revealed different electronic transitions within the molecules with the electron-donating substituents from those bearing the electron-accepting substituents, thus the electron-accepting effect on the shift of the absorption maxima being considerably stronger. The influence of the chemical structure on the pharmacokinetically relevant properties of the investigated hydantoin derivatives was evaluated using the Lipinski?s rule of five, Veber, Egan and Ghose's empirical criteria, as well as different in silico methods. When compared to phenytoin (5,5-diphenylhydantoin) as the referent drug, compounds with a halogen or electron-donating substituent are expected to possess better intestinal absorption and passage through the blood-brain barrier. Depending on the nature of the substituent present in the benzyl moiety, compounds 1a?1g and 2a?2f can be potent activators/inhibitors of some cytochrome P450 izoenzymes including CYP1A2, CYP2C19 and CYP2C9. Regarding biological activity profile, compounds with the electron-accepting substituents are likely to reveal the pharmacological potential similar to that of phenytoin, while those bearing electron-donating substituents are predicted to have the antimigrenic activity. All compounds were found to bear a low risk of being mutagenic or tumorigenic. The calculated molecular descriptors indicate that the investigated compounds fulfill necessary empirical criteria which qualify them as interesting drug candidates.

Tuning of optical properties of p-phenyl ethenyl-E-furans: A Solvatochromism and Density functional theory.

p-Phenyl ethenyl-E-furans (1-6) with varied electron donor and acceptor substituent (NO2, CN, Cl, H, OCH3, NH2) were synthesized and studied the substituent induced optical properties (dipole moment, transition dipole moment, oscillator strength, optical band gap, hyperpolarizability) using Solvatochromism and Density functional theory. It is shown that furan acts as a weak electron donor in presence of an electron withdrawing p‑phenyl substituent (NO2, CN, Cl), whereas furan acts as a weak electron acceptor in presence of an electron donating p‑phenyl substituent (OCH3, NH2). In comparison to ethenylfuran 4, the HOMO-LUMO energy band gap is decreased upon increasing the electron donating or electron withdrawing nature of the phenyl ring. Calculation of excited state dipole moment and polarizability of 1-6 in solvent of varying polarity suggest that the nitro and amino compounds (1, 6) exhibit charge transfer excited state, whereas excited state of compounds 3-5 is non-polar in nature. As compared to the ethenylfuran (4), the first hyperpolarizability (β) is increased in presence of a strong electron withdrawing or strong electron donating p‑phenyl substituent. The higher β value is found for ethenylfuran with p‑nitrophenyl and p‑amino phenyl substitution. Overall, these studies provide useful information in tuning the optical properties of p‑phenyl substituted heterocyclic ethenyl systems.

Versatility of the Biginelli reaction: Synthesis of new biphenyl dihydropyrimidin-2-thiones using different ketones as building blocks

A multi-component synthesis of biphenyl dihydropyrimidin-2-thiones from 1-phenylthiourea, aldehydes and ketones or di-ketones has been demonstrated. The reaction proceeded well for aldehydes with electron donor or acceptor substituents under mild conditions.

SYNTHESIS OF 1,5-DIPHENYL-3-ARYLVERDAZILS

The reaction between verdazyls and CH-acids was studied for checking common views on the stable radicals reactivity which is usually associated with the spin density values of the reaction centers and its alterations due to the influence of substituents. The synthesis of row l,5-diphenyl-3-arylverdazyls that contains the different types of substituents in the phenyl rings that are situated at C3 verdazyl radical atom was carried out for this purpose. This also includes the previously non-described 1,5-diphenyl-3-(4-hydroxyl)phenyl-, 1,5-diphenyl-3-(4-bromo)phenyl-, 1,5-diphenyl-3-(3- nitro)phenylverdazyls. In this case, the availability and nature of the substituents in the phenyl rings at C3 verdazyl radical atom may not be affected by the change in the spin density values on the N2 and N4 nitrogen atoms that are verdazyl radicals’ reaction centers. The synthesis of verzdazyls was carried out according to the conventional scheme, on the basis of arylhydrazones. It was observed that during azocoupling reacting of phenyldiazonium chloride with arylhydrazones in the synthesis of formazans the reaction proceeds with a higher yield when the solvent dimethylformamide-pyridine is being used. Transformation of formazans into verdazyl radicals was being carried out at room temperature with formaldehyde exposured to formazan in the presence of potassium hydrogen sulfate under the constant air going through the reactor feed. The availability of substituents in the phenyl ring at C3 formazan atom was increasing reaction time significantly in comparison with 1,3,5- trifenylformazan regardless of the substituent’s nature at C3 formazan atom. During the reaction between 1,5-diphenyl-3-arilverdazyls and CH-acids (acetylacetone and dimedone), it was discovered that the reaction rate depends on both the acidity of the CH-acid (dimedone reacts faster than acetylacetone) and the nature of the substituents situated in phenyl ring at C3 verdazyl atom. At the same time, the electron-donating substituents increase the rate of reaction between verdazyls and CH-acids while electron-donor substituents decrease it. Therefore, as it was formerly reported, when we deal with monochloroacetic acid, the rate of a reaction between verdazyl radicals and CH-acids is increasing in front of the electron-donor substituents and decreasing in front of electron-acceptor substituents. These regularities are not connected with the spin density values of the verdazyls’ reaction centers.Forcitation:Tsebulayeva Yu.V., Pryanichnikova M.K., Tanaseichuk B.S. Synthesis of 1,5-diphenyl-3-arylverdazils. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 1. P. 23-29

3,6-Di-tert-butylcatecholates of trialkyl/triarylantimony(V)

A number of 3,6-di-tert-butyl-catecholates of trialkyl- and triarylantimony(V) (3,6-DBCat)SbR3, where R is methyl (Me), n-hexyl (Hex), cyclohexyl (Cyclohex), o-tolyl (o-Tol), p-tolyl (p-Tol), p-biphenyl (p-biPh), p-fluorophenyl (p-FPh), p-chlorophenyl (p-ClPh) have been synthesized and characterized in details. The molecular structures of (3,6-DBCat)SbMe3, (3,6-DBCat)Sb(p-Tol)3 and (3,6-DBCat)Sb(p-ClPh)3·acetone were determined by single-crystal X-ray analysis. The electrochemical properties of complexes were investigated by means of cyclic voltammetry. It was shown that the electron-acceptor substituents at the central antimony atom shift the oxidation potentials of the corresponding catecholate complexes to the anodic region while electron-donor groups make the oxidation of catecholate complexes to o-semiquinolate derivatives easier.

Photoswitchable Intramolecular Hydrogen Bonds in 5-Phenylazopyrimidines Revealed By In Situ Irradiation NMR Spectroscopy.

NMR spectroscopy with in situ irradiation uncovered unique photoswitchable intramolecular hydrogen bonds (IMHBs) in 5-phenylazopyrimidines with two hydrogen bond donors. These compounds form two stable rotamers, each with one IMHB, and the rotamer ratio changes reversibly upon UV or visible light irradiation. Strong substituent dependence of photoinduced structural changes was observed; using suitable substituents, orthogonal photoswitching can be achieved. For example, whereas UV irradiation caused switching between the two rotamers of the trans isomer of a compound with electron-donating methoxy substituent, visible light enabled to obtain the cis photoisomer. No cis isomer was detected for compounds with electro-neutral or electron-accepting substituents, but photoswitching between the two trans isomers was observed. On the other hand, compounds without hydrogen-bond donors or with one donor only formed stable cis isomers. A mechanism of the photoswitching was proposed by DFT computations.

Computational study of vicarious nucleophilic substitution reactions.

Vicarious nucleophilic substitution reactions are a versatile way of introducing substituents into aromatic and heteroaromatic electron-deficient compounds. In this project, a kinetic study of these reactions by applying quantum mechanics concepts, such as reaction force, force constant, and electronic reaction flow was proposed. Furthermore, absolute theoretical scales of electrophilicity by applying density functional theory electronic indices were established to classify a series of five and six-membered nitroheteroarenes, and nitrobenzenes with substituents in ortho, meta and para positions. The theoretical model was validated by comparison with experimental kinetic results. Calculations using B3LYP/6-311G(d,p) level of theory allowed analysis of the reactivity patterns and the mechanisms of these chemical reactions. The theoretical scale properly accounts for the activating/deactivating effects promoted by the substituents and agrees with the ability of these substituents to accept or donate electrons, electron acceptor substituents are those that increase electrophilicity, and electron donors those that reduce it.

Exploring the pnicogen bond non-covalent interactions in 4-XPhNH2:PFnH3-n complexes (n = 1–3, X = H, F, CN, CHO, NH2, CH3, NO2 and OCH3)

Quantum chemical calculations were carried out to explore the effects of substituents in para position of aniline as well as phosphine on the strength of interactions in pnicogen-bonded (PB) complexes of the 4-XPhNH2:PFnH3-n (n=1–3 and X=H, F, CN, CHO, NH2, CH3, NO2 and OCH3). The P⋯N pnicogen bond strength in these complexes was examined at M06-2X/6–311++G(d,p), MP2/6–311++G(d,p), MP2/cc-pVDZ, CCSD/cc-pVDZ and MP2/aug-cc-pVTZ levels of theory. The dispersion corrected M06-2X-GD3, B2PLYP-GD3 and mPW2PLYP-GD2 functionals were also used to calculate the binding energies. The changes in the pnicogen bond strength due to the change of the substituents were well monitored by the changes in the interaction energy, structural parameters, natural charge, charge transfer, electron density topology, NMR chemical shielding and spin-spin coupling constants. The BSSE-corrected BEs change from 14.5 to 21.4kJmol−1 for the 4-XPhNH2:PF3, 21.5 to 30.5kJmol−1 for the 4-XPhNH2:PF2H and 24.2 to 33.1kJmol−1 for the XPhNH2:PFH2 complex at MP2/aug-cc-pVTZ level and 12.5 to 18.9kJmol−1 for the 4-XPhNH2:PF3, 17.4 to 26.5kJmol−1 for the 4-XPhNH2:PF2H and 18.9 to 26.5kJmol−1 for the XPhNH2:PFH2 complexes at MP2/6–311++G(d,p) level. For each PFnH3-n monomer, results demonstrated that the strength of the pnicogen bonds increases by introducimg electron-donating substituents in 4-XPhNH2 molecule, whereas a reverse situation was found upon introducing electron-accepting substituents. Natural bond orbital analysis confirmed that the charge transfer takes place from 4-XPhNH2 to PFnH3-n. Electron density properties based on atoms in molecules theory were also utilized to characterize the pnicogen bonds.

Temperature dependent spectroscopic and excited state dynamics of 3-hydroxychromones with electron donor and acceptor substituents

We have studied the photophysical and photochemical behavior of three compounds derived from 3-hydroxychromone (3-HC), capable of undergoing excited state proton transfer (ESIPT). The compounds have two substituents, located in positions 2 and 7, one on each ring of the 3-HC heterocycle. The substituent pattern shows different electron donating and acceptor features. The compounds were studied by absorption and emission spectroscopy, steady state anisotropy, and time resolved emission spectroscopy (TRES) as a function of temperature. Results were interpreted using time dependent density functional theory calculations. Compared to reference compounds of 3-HC substituted only in the 2 position, the compounds show similar absorption and emission spectra, shifted 20–30 nm to higher wavelengths due to extended conjugation. TRES shows the existence of ESIPT in the thermodynamic equilibrium regime. This process is endothermic in all three compounds. The different behavior compared to monosubstituted 3-HC is attributed to the extended conjugation and to the electron donor acceptor character of the substituents, which has a more pronounced effect when the electron acceptor is located in position 2.

Reaction of 1,5-diphenyl-3-arylverdazyles with СН-acids

The presence of electron-donor substituents in the phenyl ring at the atom С3 of the tetrazinyl ring increases, and of electron-acceptor substituents reduces the reaction rate of 1,5-diphenyl-3-arylverdazyl radicals with СН-acids. The reaction is described with a kinetic equation of the second order with respect to verdazyl, the process rate is determined by the energy of the electron transfer from the SOMO (singly occupied molecular orbital) of the radical to the LUMO of the СН-acid.

A density functional theory investigation of the interaction of the tetraaqua calcium cation with bidentate carbonyl ligands.

Calcium complexes with bidentate carbonyl ligands are important in biological systems, medicine and industry, where the concentration of Ca2+ is controlled using chelating ligands. The exchange of two water molecules of [Ca(H2O)6]2+ for one bidentate monosubstituted and homo disubstituted dicarbonyl ligand was investigated using the B3LYP/6-311++G(d,p) method. The ligand substituents NH2, OCH3, OH, CH3, H, F, Cl, CN and NO2 are functional groups with distinct electron-donating and -withdrawing effects that bond directly to the sp2 C atom of the carbonyl group. The geometry, charge and energy characteristics of the complexes were analyzed to help understand the effects of substituents, spacer length and chelation. Coordination strength was quantified in terms of the enthalpy and free energy of the exchange reaction. The most negative enthalpies were calculated for the coordination of bidentate ligands containing three to five methylene group spacers between carbonyls. The chelate effect contribution was analyzed based on the thermochemistry. The electronic character of the substituent modulates the strength of binding to the metal cation, as ligands containing electron-donor substituents coordinate stronger than those with electron-acceptor substituents. This is reflected in the geometric (bond length and chelating angle), electronic (atomic charges) and energetic (components of the total interacting energy) characteristics of the complexes. Energy decomposition analysis (EDA)-an approach for partitioning of the energy into its chemical origins-shows that the electrostatic component of the coordination is predominant, and yields relevant contribution of the covalent term, especially for the electron-withdrawing substituted ligands. The chelate effect of the bidentate ligands was noticeable when compared with substitution by two monodentate ligands. Graphical abstract The affinity of 18 bidentate carbonyl ligands toward the [Ca(H2O)4]2+ cation is evaluated in terms of energetic, geometric and electronic parameters of the isolated ligands and the substituted aqua complexes. The electronic effects-inductive and mesomeric-intrinsic to the molecular structure of each ligand are found to modulate the strength of the metal-ligand interaction. The effects of polysubstitution, chelation and the length of the alkyl spacers between the anchor points of the ligand are also analyzed.

The effect of substituted pyridine ring in the ancillary group on the electronic structures and phosphorescent properties for Ir(III) complexes from a theoretical viewpoint

The electronic structures and photophysical properties of eight phosphorescent Ir(III) complexes containing (4′-substituted-2′-pyridyl)-1,2,4-triazole ancillary ligands have been theoretically studied via density functional theory and time-dependent density functional theory calculations. The effect from the electron-donating and electron-accepting substituents on charge injection, transport, absorption, and phosphorescent properties of all the studied complexes has been investigated. The calculated results reveal that the different substituted ligands can modify the absorption and emission properties. In addition, ionization potential (IP), electron affinities (EA) and reorganization energy were obtained to evaluate the charge transfer and balance properties between hole and electron. The calculated results show that the different substitute groups affect the charge transfer rate and balance. The theoretical work can provide a description of photophysical properties through substitution, which would be useful to guide new design and synthesis of phosphorescent materials.