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Gas–particle partitioning between reactive gaseous mercury (RGM) and particle bound mercury (PBM) controls the fates of atmospheric oxidized mercury (namely reactive mercury, RM). We conducted a long-term observations of gaseous elemental mercury (GEM), RGM, PBM, and auxiliary parameters in Chongming Island, Shanghai, China, to understand the characteristics of speciated mercury and their gas–particle partitioning behaviors. The entire average abundances of GEM, RGM and PBM were 2.12 ± 0.94 ng/m3, 14.75 ± 9.94 pg/m3 and 21.81 ± 30.46 pg/m3, respectively. An observation data dependent empirical gas–particle partitioning relationship of partitioning coefficient and temperature log(1/KP) = −2692.20/T + 10.57 was obtained, and it varied in different season being by the temperature. To further evaluate the influences of temperature, particulate matter (PM), relative humidity on RGM and PBM partitioning process, the particulate fraction (φ = PBM/(PBM + RGM)) was used in this study. High φ values (φ > 0.8) mainly occurred at low temperature domain (<281 K), and high PM concentration enhanced this influence. In addition, high relative humidity shifts RGM from atmosphere partitioning to PBM in response to the diurnal valley φ values at 13:00–16:00 in the summer. Photochemical reactions were proposed to play important roles on partitioning processes between RGM and PBM. This study will benefit for the understanding of oxidized mercury fate and influencing factors in the complex atmospheric pollutants. [ABSTRACT FROM AUTHOR]

By using the density functional theory (DFT) and time-dependent density functional theory (TDDFT), the electronic structure and photophysical properties of a series of cyclometalated iridium(III) complexes bearing the substituted phenylpyrazole have been theoretically investigated. All studied iridium(III) complexes have the distorted octahedral geometry with cis-C,C, cis-O,O, and trans-N,N chelate disposition. The lowest lying singlet → singlet absorptions of all studied iridium(III) complexes are respectively located at 405 nm, 387 nm, 382 nm, 370 nm, and 387 nm. The calculated emission wavelengths for all studied iridium(III) complexes are 654 nm, 513 nm, 506 nm, 505 nm and 499 nm, respectively. The calculated emission wavelength for complex 4 at the CAM-B3LYP level is in good agreement with the experimental value. From the theoretical results, it can be seen that the electron-donating substituent groups have the important effect on the electronic structure and photophysical properties of all studied iridium(III) complexes. We hope that this study can provide valuable guidance for the design of new phosphorescent organic light-emitting diodes (OLEDs) materials. [ABSTRACT FROM AUTHOR]

The electronic structure and photophysical properties of three iridium(III) complexes bearing tridentate chromophoric chelate have been theoretically studied by using the DFT/TDDFT. The lowest lying singlet→singlet absorptions of all studied complexes are respectively located at 363 nm, 394 nm and 353 nm. The calculated emission wavelengths for all studied complexes are 503 nm, 486 nm and 493 nm, respectively. The calculated results show that the electron-accepting and electron-donating substituent groups have the important effect on the electronic structure and photophysical properties of all studied iridium complexes with tridentate ligands. [ABSTRACT FROM AUTHOR]

The electronic structure and photophysical properties of a series of iridium(III) complexes have been theoretically explored by DFT/TDDFT calculations. Ionization potential, electron affinities, and reorganization energy have been calculated to evaluate the charge transfer and balance properties between hole and electron for the three complexes. The lowest lying absorption of 3 is obviously blue-shifted in contrast to those of 1 and 2, which is consistent with the variation of the energy gap between of LUMO and HOMO values. The calculated lowest energy emissions of complexes 1, 2 and 3 are located at 607, 634 and 698 nm, respectively. [ABSTRACT FROM AUTHOR]

The electronic structure and photophysical properties of two series of iridium(III) complexes with a four-membered Ir–S–C–S chelating ring have been theoretically studied using the density functional theory (DFT) and time-dependent density functional theory (TDDFT) method. The calculated geometrical parameters for complexes 1c and 2c are in good agreement with the available experimental values. Furthermore, 1c and 2c possess the smallest ΔEL→H levels in the two series of complexes, respectively. The lowest lying absorption of 1c (2c) has the obvious redshift in contrast to those of 1a (2a) and 1b (2b). The lowest emission wavelengths of 1b (2b) and 1c (2c) have the obvious blue-shift and red-shift, respectively, in comparison with those of 1a (2a), which indicates that the introduction of the benzene ring into a different position in the main ligand has a different effect on the photophysical properties. The calculated results show that extending the π-conjugation of the main ligand can tune the emission of the iridium complex and has an important effect on the photophysical properties. The complex 2c possibly possesses the largest kr value among all studied complexes. It is expected that this study can be useful to understand the relationship between the structure and properties and develop efficient phosphorescent materials. [ABSTRACT FROM AUTHOR]

• Photophysical properties of two series of iridium(III) complexes have been theoretically investigated. • Calculated emission wavelength of 1a is in agreement with the experimental datum. • Complex 2b possibly possesses the largest k r value in all studied complexes. The electronic structure and photophysical properties of two series of iridium(III) complexes have been theoretically investigated by using the density functional theory (DFT) and time-dependent density functional theory (TDDFT) method. The effect of the electron-withdrawing and electron-donating substituents on absorption and phosphorescent properties has been investigated. All studied complexes have multiple ultraviolet-visible light absorption peaks. The theoretical emission wavelength for 1a is very close to the experimental value. Complex 2b possibly possesses the largest k r value in all studied complexes. It is anticipated that our findings here can provide a valid way for developing good phosphorescent iridium(III) complexes in organic light-emitting diodes (OLEDs). [Display omitted] [ABSTRACT FROM AUTHOR]

By using density functional theory and time-dependent density functional theory, the geometrical, electronic and photophysical properties of six complexes with two ppy-type ligands and one acetylacetone anion around the Ir center have been explored. The lowest energy absorption wavelengths are located at 414 nm for 1, 434 nm for 2, 434 nm for 3, 421 nm for 4, 436 nm for 5, and 425 nm for 6, respectively. The lowest energy emissions of these complexes are localized at 617, 492, 633, 634, 491 and 491 nm, respectively, for complexes 1–6, simulated in CH2Cl2 medium at the M062X level. The calculated lowest lying absorption wavelength and the lowest energy emission wavelength for complex 3 are very close to the available experimental values. The position and number of the incorporated electron-withdrawing fluorine substituents have some effect on the electronic and photophysical properties of these studied complexes. [ABSTRACT FROM AUTHOR]

By using the density functional theory/time-dependent density functional theory methods, the electronic structure and photophysical properties of five heteroleptic cyclometalated Ir(III) complexes have been studied. The lowest absorption wavelengths are located at 350 nm for 1, 352 nm for 2, 354 nm for 3, 400 nm for 4 and 352 nm for 5, respectively. The phosphorescence wavelength of complexes 1–5 are localized at 445, 473, 474, 490 and 466 nm, respectively, simulated in CH2Cl2 medium at CAM-B3LYP level. It is expected that the theoretical results could help the experimentalists in synthesizing new excellent emitters for organic light-emitting diodes. [ABSTRACT FROM AUTHOR]

A DFT/TDDFT (density functional theory/time-dependent density functional theory) investigation on the geometries in the ground and lowest triplet excited states, the frontier molecular orbitals, the absorption spectra and the phosphorescent emission properties of five heteroleptic iridium(iii) complexes have been performed to obtain a better understanding of structure–property relationships. The key aim was to investigate the effect of π-conjugation on the photophysical properties of these studied complexes. The lowest energy absorption wavelengths are located at 461 nm for 1, 418 nm for 2, 422 nm for 3, 426 nm for 4 and 417 nm for 5. The lowest energy emissions of complexes 1–5 are localized at 572, 463, 583, 707 and 553 nm, respectively, simulated in acetonitrile medium at M052X level. These findings could be useful to provide good guidance for the further design of new potential phosphorescent organic light-emitting diode (OLED) materials. [ABSTRACT FROM AUTHOR]

Abstract A two-year gaseous elementary mercury (GEM) measurement was implemented at an iron–steel plant in Yangtze River Delta, China, which provided an excellent opportunity to investigate their dynamic cycling. The hourly GEM concentrations ranged between 0.78 and 113.8 ng m−3, with a mean value of 3.83 ± 2.53 ng m−3. Temporally, seasonal GEM contents decreased as winter ≈ spring > summer > autumn, while diurnal cycling was observed with a steady decrease at 14:00–17:00. GEM variations were found to be related to source emissions, meteorology and regional transportation. Three major oxidants (O 3 , Br and OH radicals) were used to evaluate GEM oxidation in the daytime, and the estimated GEM depletion rate was 70.8 ± 52.5 molecule cm−3 s−1 (0.09 ± 0.06 ng m−3 h−1). The GEM oxidized by Br radicals accounted for 83.4% of the total GEM oxidation rate, followed by O 3 (13.8%). The estimated atmospheric lifetime of GEM was 22.9 to 345.2 days, which implies a major contribution of Br radicals to the GEM sink. These findings highlight the ability of iron–steel industry emissions and in–situ oxidation to affect daily local GEM cycling significantly. Graphical abstract Simplified mechanisms of GEM oxidization by atmospheric oxidant radicals in the iron-steel industry. Unlabelled Image Highlights • A two-year-time hourly measurement of gaseous elemental mercury was implemented in an iron-steel plant in China. • The observed hourly GEM concentrations ranged between 0.78 to 113.8 ng m-3, with a mean value of 3.83 ± 2.53 ng m-3. • The GEM oxidation rate initiated by three major oxidants (O 3 , Br· and OH· radicals) were evaluated. • The calculated GEM lifetime against oxidation ranged from 22.9 to 345.2 days. [ABSTRACT FROM AUTHOR]

Graphical abstract The photophysical properties of six phosphorescent heteroleptic iridium(III) complexes with different monodentate ligands have been theoretically investigated. Abstract Density functional theory (DFT) and time-dependent density functional theory (TDDFT) calculations have been employed to study the geometrical structures, electronic structures and photophysical properties of six heteroleptic iridium(III) complexes. The key aim is to investigate the effect of substituent groups with different conjugation length and different electron-donating/withdrawing ability on photophysical properties for these studied complexes. The lowest energy absorption wavelengths are located at 416 nm for 1 , 426 nm for 2 , 458 nm for 3 , 470 nm for 4 , 459 nm for 5 and 439 nm for 6 , respectively. The lowest energy emissions of complexes 1 – 6 are localized at 559, 722, 890, 914, 648 and 768 nm, respectively, simulated in tetrahydrofuran medium at VSXC level. Furthermore, ionization potential (IP), electron affinities (EA) and reorganization energy (λ hole/electron) have also been studied to evaluate the charge transfer and balance properties between hole and electron. It could be useful to design and synthesize potential phosphorescent organic light-emitting diodes (OLEDs) materials. [ABSTRACT FROM AUTHOR]

Petroleum related emissions are the major anthropogenic sources of volatile organic compounds (VOCs), which served as important precursors for secondary organic aerosol (SOA). However, little is known about the relationship among VOCs emissions from petrochemical industries, SOA formation, and regional PM 2.5 . In this paper, VOCs emitted from a petrochemical industry in Yangtze River Delta (YRD, China) were continuously monitored by an online gas chromatography-photo ionization detector/flame ionization detector (GC-PID/FID) system. Results showed that the total concentration of 68 VOCs species was 151.0 ± 155.6 ppbv, and ethylene, ethane, 2-methylpentane, chloroform, 2,3-dimethyl-butane and propane were the richest species. SOA yield calculated by time-resolved approach was 7.18 ± 10.97 μg m −3 , accounted for 3.35–86.4% of the corresponding PM 2.5 concentration, which was a bit higher than previously reported values. VOCs-sensitiveness (VOCs-S) coefficient was adopted to investigate the quantitative relationship between VOCs and PM 2.5 , found VOCs were more sensitive to PM 2.5 in clean domains than in polluted domains. An exponential function was fitted (y = 3.94x 0.293 – 3.62, r 2  = 0.816) between VOCs-S coefficient versus specific-to-background PM 2.5 ratio for aromatic hydrocarbon. VOCs emitted from petrochemical industry had influence on regional PM 2.5 in this study, and reducing petrochemical emissions might be effective in alleviating haze episodes. [ABSTRACT FROM AUTHOR]

The photophysical properties of four Ir(III) complexes have been investigated by means of the density functional theory/time-dependent density functional theory (DFT/TDDFT). The effect of the electron-withdrawing and electron-donating substituents on charge injection, transport, absorption and phosphorescent properties has been studied. The theoretical calculation shows that the lowest-lying singlet absorptions for complexes 1-4 are located at 387, 385, 418 and 386 nm, respectively. For 1-4, the phosphorescence at 465, 485, 494 and 478 nm is mainly attributed to the LUMO → HOMO and LUMO → HOMO-1 transition configurations characteristics. In addition, ionisation potential (IP), electron affinities (EAs) and reorganisation energy have been investigated to evaluate the charge transfer and balance properties between hole and electron. The balance of the reorganisation energies for complex 3 is better than others. The difference between hole transport and electron transport for complex 3 is the smallest among these complexes, which is beneficial to achieve the hole and electron transfer balance in emitting layer. [ABSTRACT FROM AUTHOR]

To investigate the influence of the different substituents in the main ligands on the electronic structures, phosphorescent properties, and organic light-emitting devices (OLEDs) performance, three iridium(III) complexes 1, 2, and 3 are studied by means of the density functional theory/time-dependent density functional theory (DFT/TDDFT). Ionization potential, electron affinities, and reorganization energy have also been obtained to evaluate the charge transfer and balance properties between hole and electron for the three complexes. The lowest energy absorption wavelength calculated for complex 1 is in very good agreement with the experimental value. The lowest energy emissions of complexes 1, 2, and 3 are localised at 492, 565, and 510 nm, respectively, at M052X level. It is expected that this work might provide a way to develop potential iridium(III) phosphors with good electroluminescent performance. [ABSTRACT FROM AUTHOR]

The photophysical properties of a series of platinum(II) complexes have been theoretically investigated. The effect of the electron-withdrawing and electron-donating substituents on charge injection, transport, absorption and phosphorescent properties has been studied. For complexes1–5, the phosphorescence at 474, 453, 451, 524 and 461 nm are assigned to3MLCT(triplet metal-to-ligand charge transfer)/3ILCT(triplet intraligand charge transfer). In addition, ionization potential (IP), electron affinities (EA) and reorganization energy have also been analyzed to evaluate the charge transfer and balance properties between hole and electron. The calculated results show the complex2possibly possesses the largest radiative decay rate value among these studied complexes. [ABSTRACT FROM PUBLISHER]

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. [ABSTRACT FROM AUTHOR]

Two series of osmium(II) complexes with different substituent groups (-CF3, -N(CH3)2) have been studied by using the density functional theory (DFT) and time-dependent density functional theory (TDDFT) methods, to investigate their electronic structures, absorption, and emission properties. The influence of different substituted groups on their photophysical properties has also been explored. The lowest energy absorption and emission wavelengths calculated are in good agreement with the available experimental values. Besides, ionization potential (IP), electron affinities (EA), and reorganization energy (λ) were calculated to evaluate the charge transfer and balance properties between hole and electron. It is expected that the theoretical studies could provide valuable information for the phosphorescent osmium(II) material for use in the organic light-emitting diodes. [ABSTRACT FROM PUBLISHER]

Three heteroleptic iridium(III) complexes 1, 2 and 3 bearing two cyclometalating 2′,6′-difluoro-2,3′-bipyridyl (dfpypy) chelates and one pyridyl pyrazolate ligand have been investigated by using the density functional theory/time-dependent density functional theory method to study the influence of the different substituent groups (―CF3and ―N(CH3)2moiety on the electronic structures, phosphorescent properties and the organic light-emitting diode performance. The lowest energy absorption wavelength calculated is in good agreement with the experimental value. The lowest energy emissions of complexes1,2and3are localised at 454, 534 and 821 nm, respectively. Ionisation potential and electron affinity have been calculated to evaluate the injection abilities of holes and electrons into these complexes. The calculated results show that the different substitute groups affect the charge transfer rate and balance. Finally, we hope that this study can provide a good guide to the future design and synthesis of novel phosphorescent materials for use in the organic light-emitting diodes. [ABSTRACT FROM AUTHOR]

Organoarsenics are widely used as growth promoters in poultry industry, resulting in arsenic (As) accumulation in poultry litter. A greenhouse pot study was implemented to investigate the fate of arsenic originated from poultry litter and their effects on the growth of Brassica napus (oilseed rape), and assess their potential health risks. Five poultry litter application rates (0, 5%, 10%, 20% and 40%) were used, dividing into two groups: one for soil incubation (SI) and the other for plant cultivation (PC). Experimental results indicated that the total arsenic for composted poultry litter was (10.94±0.23) mg/kg, As(V) and As(III) decreased while methylated arsenic increased after 21 d in SI and PC treatments. Seed germination rates were negatively correlated with monomethylarsenic acid (MMA, R2=0.63, p<0.05). The length and biomass of roots and shoots were significantly inhibited by poultry litter, but plant length of 5% treatments was slightly stimulated. Within an average weekly intake of 0.5 kg Brassica napuss, the risk quotient (RQ) values induced from roots nearly all surpassed the acceptable limit (1), were two orders magnitude higher than shoots. According to the potential risk to order, child exhibited the highest risk, adolescent ranked secondly, and adult exhibited the lowest risk. Hence, people should better avoid intake Brassica napus roots to reduce arsenic potential risk. [ABSTRACT FROM AUTHOR]

A DFT/TDDFT investigation has been conducted on two series of cyclometalated iridium(III) complexes to shed light on the effects of structure and steric factors on the photophysical properties. The results reveal that the nature of the N substitution can influence the electron density distributions of the frontier molecular orbitals and their energies, resulting in a change in transition character and emission color. The absorption spectra of the complexes are similar to each other, with 2a- 5a and 2b- 5b presenting a slight redshift compared with their parent complexes. Again, on the basis of the calculations, the higher radiative rate constants ( kr) of 1a- 5a with respect to 1b- 5b can be explained by a larger metal contribution to the excited states (MLCT%) and larger S0-S1 transition electric dipole moments ( µ [ABSTRACT FROM AUTHOR]

The electronic and photophysical properties of a series of iridium(III) complexes based on amidate ancillary ligand have been investigated using the density functional theory (DFT) and time-dependent density functional theory (TDDFT). Ionization potential (IP), electron affinities (EA) and reorganization energy ( λ hole/electron ) have also been obtained to evaluate the charge transfer and balance properties between hole and electron. The absorption and emission properties can be altered by the different electron-withdrawing and electron-donating substituents in the N-acetylaniline. The calculated lowest energy emissions for 1 – 6 are localized at 542, 538, 535, 557, 538, and 495 nm, respectively. It can also be seen that the complex 4 and 6 have possibly the largest and smallest k r values than among these complexes. It is anticipated that the theoretical work can be useful for designing promising phosphorescent materials for use in the organic light-emitting diodes. [ABSTRACT FROM AUTHOR]

A series of substituted platinum(II) complexes with a chelating N-heterocyclic carbene (NHC) ligand and a bidentate monoanionic auxiliary ligand (acetylacetone) have been investigated by using the density functional theory (DFT) and time-dependent density functional theory (TDDFT) methods, to explore their electronic structures, absorption and emission properties, and phosphorescence quantum efficiency. The influence of different substituted groups on photophysical properties of complexes studied has been detailedly analyzed. The lowest energy absorption and emission wavelengths calculated are comparable to the available experimental values. In addition, ionization potential (IP), electron affinities (EA), and reorganization energy (λ) were obtained to evaluate the charge transfer and balance properties between hole and electron. The calculated results also show that, due to a lower, larger3MLCT contribution, and highervalue, the complex5owns possibly the largestkrvalue among these complexes. The theoretical studies could provide useful information for the candidated phosphorescent platinum(II) material for use in the organic light-emitting diodes. [ABSTRACT FROM AUTHOR]

The oceans, serving as some of the most extensive reservoirs of mercury (Hg) on Earth, play an essential role in the global Hg biogeochemical circulation, as a sink for atmospheric deposits and surface runoff while simultaneously emitting Hg to the atmosphere. Clarifying the mechanisms during cycling of Hg in marine ecosystems is a crucial segment in elucidating global Hg behavior and assessing its risks to wildlife and humans. The stable Hg isotope technique has emerged as a powerful tool for identifying potential sources and certain processes of Hg. Herein, the research advances in marine Hg biogeochemical cycling were reviewed from an isotopic tracing perspective, including sources of marine Hg, isotopic fingerprints across various marine media, and applications of Hg isotopes in pathways, transport, and transformation mechanisms associated with marine environments. The knowledge gaps and challenges were further discussed in the development of ultratrace level and species-specific isotopic analytical methods, the isotope fractionation mechanisms in reactions and processes, and the integration of multiple approaches and cross disciplines. These future studies would advance our understanding of Hg behavior in oceanic environments, its authentic function, and interactions with other ecosystems in the global Hg cycle, and evaluate its response to environmental changes. [ABSTRACT FROM AUTHOR]

The electronic and photophysical properties of a series of substituted N -heterocyclic carbene (NHC) platinum(II) complexes have been investigated by using the density functional theory (DFT) and time-dependent density functional theory (TDDFT) methods. The lowest-lying singlet absorptions for complexes 2 – 5 are attributed to the configurations of HOMO (highest occupied molecular orbital) to LUMO (lowest unoccupied molecular orbital). The emission energies for these complexes are obviously red-shifted in contrast to that of 1 . For 3 and 4 , the emission energies are nearly the same, consistent with their same energy gaps between of LUMO and HOMO. In addition, ionization potential (IP), electron affinities (EA) and reorganization energy ( λ ) also were obtained to evaluate the charge transfer and balance properties between hole and electron. From the calculated results, it can be seen that the complex 3 possesses possibly the largest k r value among these complexes due to the lowest Δ E S 1 − T 1 , larger 3 MLCT contribution, and higher μ S 1 ⁡ value. It is anticipated that this study could provide useful information for the synthesis of efficient platinum(II) phosphors in OLEDs. [ABSTRACT FROM AUTHOR]

The electronic structures and phosphorescence efficiency for two series of Ir(III) complexes with different substituent groups were theoretically investigated by using density functional theory (DFT) and time-dependent DFT (TDDFT) methods. The results reveal that the nature of the different substituents can influence the electron density distributions of frontier molecular orbitals and their energies, resulting in the change of transition character and emission color, while the different number of –(CH 2 CH 2 O)– units have an impact on the HOMO and LUMO energy levels of the designed complexes 2a – 6a and 2b – 6b . It can be speculated that the complexes 1a – 4a and 1b – 5b are considered to be potential candidates as blue-emitting materials. The assumed complexes 6a and 6b also are the potential candidate as an efficient green-emitting material with high photoluminescent quantum yield. [ABSTRACT FROM AUTHOR]

Two series of platinum(II) complexes with triarylboron/triarylnitrogen-functionalized N-heterocyclic carbene chelate ligands have been theoretically investigated by using the density functional theory (DFT) and time-dependent DFT (TDDFT) methods. The influence of different substituents (triarylboron-functionalized or triarylnitrogen-functionalized) on the electronic structure and optical properties of Pt(II) complexes was also explored. The results reveal that the different substituents can influence the electron density distributions of frontier molecular orbitals and their energies, resulting in the change of transition character and emission color. The designed complex 1b and 1d are considered to be a potential candidate as deep blue-emitting material. [ABSTRACT FROM AUTHOR]

A theoretical investigation was performed on a series of platinum(II) complexes with the dipivaloylmethane as ancillary ligand and tetrahydroquinolines with different substituent group (–CF3, –CN, –H, –CH3, and –OCH3) as C^N cyclometalating ligand. The geometry structures, electronic structures, absorption, and phosphorescent properties of these platinum(II) complexes have been investigated. Ionization potential and electron affinity were calculated to evaluate the injection abilities of holes and electrons into these complexes. The lowest energy absorption wavelengths are located at 362 nm for1, 372 nm for2, 361 nm for3, 361 nm for4, and 355 nm for5, respectively. The lowest energy emissions of these complexes are localized at 520, 544, 513, 519, and 523 nm, respectively, for complexes1–5, simulated in CH2Cl2medium at M062X level. The calculated results indicate that the complex2possibly possesses the largest krvalue among the five complexes. It is expected that the study can be useful for designing and synthesizing the new phosphorescent OLEDs materials. [ABSTRACT FROM AUTHOR]

Based on the complexes [Ir(dfb-pz)2(tfmtyp)] (1) and [Ir(tfmfb-pz)2(tfmtyp)] (2) [dfb-pz = 2,4-difluorobenzyl-N-pyrazole; tfmtyp = 2-(5-trifluoromethyl-[1,2,4]triazol-3-yl)-pyridine; tfmfb-pz = 2-tri-fluoromethyl-5-fluorobenzyl-N-pyrazole], two series of Ir(iii) complexes have been designed by substituting “CH” groups with the N atom at -a, -b, -c, and -d positions on the pyridine moiety in N^N ligands. The electronic structure, absorption and emission spectra as well as phosphorescence efficiency of all these Ir(iii) complexes were investigated by using density functional theory (DFT) and time-dependent DFT (TDDFT) methods. The calculated results show that the assumed complexes 1a and 2a may possess a higher photoluminescent quantum efficiency than other complexes and are potential candidates as efficient blue-emitting materials. This study shows that the N substitution can tune the emission color of 1 and 2 and enhance the photoluminescence quantum efficiency. [ABSTRACT FROM AUTHOR]

The geometry structures, electronic structures, absorption and phosphorescent properties of a series of iridium(III) complexes with the different N-substitution cyclometalating ligand and the same benzyldiphenylphosphine auxiliary ligand have been theoretically investigated by using the density functional theory method. The lowest energy absorption wavelengths are located at 378 nm for A , 430 nm for B , 411 nm for C , 436 nm for D , and 394 nm for E . The introduction of N atom substitution at 1-, 2-, 3-, and 4-positions on the pyridyl moiety of complex A leads to an obvious redshifted absorption. The lowest energy emissions for complexes A – E are localized at 450, 409, 438, 483, and 429 nm, respectively, simulated in CH 2 Cl 2 medium at M052X level. Ionization potential and electron affinity have been calculated to evaluate the injection abilities of holes and electrons into these complexes. For complex C , the calculated results showed that it can possibly possess the larger radiative decay rate ( k r ) value than those of other four complexes. It is anticipated that the theoretical studies can provide valuable information for designing new phosphorescent metal complexes of organic light-emitting diodes. [ABSTRACT FROM AUTHOR]

The geometrical structures, electronic structures, absorption and phosphorescent properties of a series of osmium(II) complexes with the structure (N^N) 2 Os(P^P) [where N^N = 2-pyridyl phenyl triazolate, P^P = 1,2-bis(phospholano)methylene ( 1 ); 1,2-bis(phospholano)ethane ( 2 ); 1,2-bis(phospholano)-4-methyl-benzene ( 3 ); 1,2-bis(phospholano)benzene ( 4 ); 1,2-bis(phospholano)-4-cyano-benzene ( 5 ); 1,2-bis(phospholano)naphthalene ( 6 )] have been investigated using density functional theory (DFT) and time-dependent density functional theory (TDDFT). Ionization potential and electron affinity values indicate that complex 5 has a good charge transfer balance to enhance device performance of organic light-emitting diodes (OLEDs). The lowest energy emissions of complexes 1 – 6 at the PBE0 level are localized at 663, 656, 660, 659, 647 and 656 nm, respectively. From the theoretical results, it can be predicted that complex 3 has possibly a larger k r value than the other complexes. These theoretical studies could be useful in providing valuable information on the optical and electronic properties of phosphorescent materials used in organic light-emitting diodes (OLEDs). [ABSTRACT FROM AUTHOR]

The electronic structures, photophysical properties, and potential organic light-emitting diodes (OLEDs) applications of a series of Ir(III) complexes 1 – 6 have been theoretically investigated by using the density functional theory (DFT) method. The photophysical properties of these complexes are greatly affected by the different substituents on the cyclometalated ligands. The phosphorescence wavelength, quantum yields, and luminescent efficiency of these complexes also are closely related to the π-conjugation length, substitution positions, and substituents inductive effect for the cyclometalated ligands. The designed complex 5 could be a potential candidate as a blue-emitting material with a high quantum efficiency. [ABSTRACT FROM AUTHOR]

Theelectronic structures and phosphorescent properties of a seriesof heteroleptic iridium(III) complexes (mpmi)2Ir(dmpypz)(1; mpmi = 1-(4-tolyl)-3-methylimidazolium, dmpypz =3,5-dimethyl-2-(pyrazol-3-yl)pyridine), (bpmi)2Ir(dmpypz)(2; bpmi = 1-biphenyl-4-yl-3-methylimidazole), (dfmi)2Ir(dmpypz) (3; dfmi = 1-(2,6-difluorobiphenyl)-3-methylimidazole),(mtmi)2Ir(dmpypz) (4; mtmi = 1-methyl-3-(4′-(trifluoromethyl)biphenyl-4-yl)imidazole),(fmmi)2Ir(dmpypz) (5; fmmi = 1-(fluoren-2-yl)-3-methylimidazole),and (mhmi)2Ir(dmpypz) (6; mhmi = 1-methyl-3-phenanthren-2-ylimidazole)have been investigated by using density functional theory (DFT) andtime-dependent density functional theory (TDDFT) methods. The influenceof different substituent groups and π-conjugation degrees onthe optical and electronic properties of Ir(III) complexes was alsoexplored by introducing phenyl, fluorophenyl, (trifluoromethyl)phenyl,and rigid construction on the phenylimidazole moiety of a cyclometalatedligand (C∧C) in complex 1. The calculatedresults show that the lowest energy absorption wavelengths of complexes 1–6are 387, 380, 378, 375, 391, and 384nm, respectively. The introduction of different substituent groupsleads to different degrees of red shift for complexes 2–6in emission spectra in comparison with thatof complex 1. It is believed that the highest tripletmetal to ligand charge transfer 3MLCT (%) contribution,smallest ΔES1–T1and higher μS1values,and larger 3MC–3MLCT energy gap for 3ensure its higher quantum yield in comparison with thatof other complexes. [ABSTRACT FROM AUTHOR]

The geometry structures, electronic structures, absorption, and phosphorescent properties of a series of iridium(III) complexes with the structure Ir(N^C^N)(N^C)Cl, (N^C^N represents a terdentate coordination with different substituent groups C2H5(1), NH2(2), CH3(3), H (4), CN (5), NO2(6), and CF3(7), N^C is 2-phenylpyridine) have been investigated using the density functional theory and time-dependent density functional theory. Calculations of ionisation potential and electron affinity were used to evaluate the injection abilities of holes and electrons into these complexes. The lowest energy absorption wavelength calculated is in good agreement with the experimental value. The lowest energy emissions of complexes1−7are localised at 552, 559, 549, 517, 627, 788, and 574 nm, respectively, at CAM-B3LYP level. For complexes1and3, the calculated results showed a lowerand larger3MLCT contributions and highervalues, which could result in the largerkrvalue than those of other complexes. It is anticipated that the theoretical studies can provide useful information for designing and synthesising the candidated phosphorescent material for use in the organic light-emitting diodes. [ABSTRACT FROM AUTHOR]

Highlights: [•] Five Ir(III) complexes have been theoretically investigated. [•] The different substituents affect the charge transfer rate and balance. [•] The calculated photophysical properties have a good agreement with the experimental data. [Copyright &y& Elsevier]

Highlights: [•] Seven tris-cyclometalated iridium(III) complexes have been theoretically studied. [•] The substituted groups have the important effect on the photophysical properties. [•] Complex 5 possibly possesses the largest k r value among the seven complexes. [ABSTRACT FROM AUTHOR]

The geometry structures, electronic structures, absorption, and phosphorescent properties of four Ir(III) complexes have been investigated using the density functional method. Calculations of ionization potential (IP) and electron affinity (EA) were used to evaluate the injection abilities of holes and electrons into these complexes. The result also indicates that the –CF3substituent group on the ligand not only change the character of transition but affect the rate and balance of charge transfer. The lowest energy absorption wavelengths are located at 428 nm for1a, 446 nm for1b, 385 nm for2a, and 399 nm for2b, respectively, in good agreement with the energy gap (ΔEL-H) trend because the HOMO–LUMO transition configurations are predominantly responsible for theS0→S1transition.2bhas the 433 nm blue emission, which might be a potential candidate for blue emitters in phosphorescent dopant emitters in organic light emitting diodes (OLEDs). The study could provide constructive information for designing novel OLEDs materials in the future. [Supplemental materials are available for this article. Go to the publisher's online edition of Molecular Crystals and Liquid Crystals to view the free supplemental file.] [ABSTRACT FROM PUBLISHER]

The geometry structures, electronic structures, absorption, and phosphorescence properties of three heteroleptic cyclometalated iridium(III) complexes have been theoretically investigated by the density functional theory (DFT) method. The highest occupied molecular orbital (HOMO) of the three complexes has the similar distributions on two main ligands. However, the lowest unoccupied molecular orbital (LUMO) of the three complexes has different distributions on different ligand fragments. Especially for 3, the LUMO is mainly composed of the picolinate auxiliary ligand. The lowest lying absorptions were calculated to be at 409, 473, and 414 nm for 1–3, respectively. By changing the conjugation length of the main ligand from 1 to 2, one can tune the emission color from green to red. The addition of sterically bulky phenolic substituents in3also results in an obvious red shift of the emission wavelength. The calculated results show that the absorption and emission transition character can be changed by altering the main ligands. Calculations of ionization potential (IP) and electron affinity (EA) were used to evaluate the injection abilities of holes and electrons into these complexes. The theoretical work should provide a suitable guide to the future design and synthesis of novel phosphorescent materials for use in the organic light-emitting diodes (OLEDs). [ABSTRACT FROM AUTHOR]

Abstract: We have reported a theoretical analysis of a series of heteroleptic iridium(III) complexes (mpmi)2Ir(pybi) [mpmi=1-(4-tolyl)-3-methyl-imidazole, pybi=2-(pyridin-2-yl)-benzo[d]imidazole] (1a), (fpmi)2Ir(pybi) [fpmi=1-(4-fluoro-phenyl)-3-methyl-imidazole] (1b), (tfpmi)2Ir(pybi) [tfpmi=1-methyl-3-(4-trifluoromethyl-phenyl)-imidazole] (1c), (pypmi)2Ir(pybi) [pypmi=3-(3-methyl-imidazol)-pyrazole] (2a), (phpymi)2Ir(pybi) [phpymi=3-(3-methyl-imidazol)-5-phenyl-pyrazole] (2b), and (inpymi)2Ir(pybi) [inpymi=3-(3-methyl-imidazol)-indeno[1,2-c]pyrazole] (2c) by using the density functional theory (DFT) method to investigate their electronic structures and photophysical properties and obtain further insights into the phosphorescent efficiency mechanism. By changing cyclometalated ligands, the conjugation length, and substituents of the cyclometalated ligands, one can tune the emission color from green (λ em=520nm) to orange (λ em=592nm). Complexes 1a, 1b, 2a, and 2b have the almost identical emission wavelength about 550nm, while 592nm for 1c and 520nm for 2c are red shifted and blue shifted, respectively, relative to 1a. The calculated results indicate that, for 1b and 1c, the substituents of −F and −CF3 at the phenyl moiety cause a poor hole-injection ability compared with that of 1a. For all these complexes studied, the hole-transporting performances are better than the electron-transporting ones. The difference between reorganization energies for hole transport (λ ih) and reorganization energies for electron transport (λ ie) for complex 1c are relatively smaller, indicating that the hole and electron transfer balance could be achieved more easily in the emitting layer. The alteration of cyclometalated ligands with different conjugation lengths and substituents has an impact on the optoelectronic properties of these complexes. It is believed that the larger metal to ligand charge transfer (MLCT) character, the highest and values, and the smallest value could result in the larger phosphorescent quantum efficiency for 2c than other complexes. [Copyright &y& Elsevier]

The geometry structures, electronic structures, absorption and phosphorescent properties of four Ir(III) complexes {[(F2-ppy)2Ir(pta-X)], where F2-ppy = (2,4-difluoro)phenylpyridine; pta = pyridine-1,2,4-triazole;X= –CF3; –H; –CH3; –N(CH3)2}, are investigated using the density functional method. The results reveal that the electron-accepting group –CF3has no obvious effect on absorption and emission properties, while the substitutive group –N(CH3)2with strong electron-donating ability has obvious effect on the emission properties. The mobility of hole and electron were studied computationally based on the Marcus–Hush theory. Calculations of ionisation potential and electron affinity were used to evaluate the injection abilities of holes and electrons into these complexes. We hope that this theoretical work can provide a suitable guide to the future design and synthesis of novel phosphorescent materials for use in the organic light-emitting diodes. [ABSTRACT FROM AUTHOR]

The geometry structures, electronic structures, absorption, and phosphorescence properties of four tris-cyclometalated iridium(III) complexes IrL3, that is, 1 (L = 2-(4,6-difluorophenyl)pyridinato,N,C2′), 2 (L = 2-(4,6-difluorophenyl)pyridinato,N,C2′-5-phenyl), 3 (L = 2-(4,6-difluorophenyl)pyridinato,N,C2′-5-( p-tolyl)), and 4 (L = 2-(4,6-difluorophenyl) benzo[ h]isoquinoline), have been investigated under the framework of the time-dependent density functional theory approach. For assumed 2 and 3, the emission energies are nearly the same, consistent with their similar HOMO−LUMO energy gaps. The calculated lowest energy emissions are localized at 523, 605, 616, and 642 nm for 1, 2, 3, and 4, respectively. Calculations of ionization potential and electron affinity were used to evaluate the injection abilities of holes and electrons into these complexes. For 2, the calculated results evidenced a larger 3MLCT contribution (27.0%), a large S0 → S1 transition dipole moment () of 1.43 D, and a small S1−T1 splitting energy () of 0.33 eV, which could result in a large radiative decay rate ( kr). We hope that this theoretical work can provide a suitable guide to the future design and synthesis of novel phosphorescent materials for use in the organic light-emitting diodes. [ABSTRACT FROM AUTHOR]

Highlights: [•] Phosphorescence properties of a series of heteroleptic iridium(III) complexes have been theoretically investigated. [•] The –CF3 substitution at different positions at ancillary ligands may be an efficient approach of tuning emitting color. [•] The assumed complex 6 is considered to be potential candidate of blue-emitting material with high quantum yield. [Copyright &y& Elsevier]

The electronic structures and photophysical properties of several heteroleptic iridium(III) complexes Ir(C∧N)2(acac) with acetylacetonate (acac) ligand, including 1 [C∧N = 2-phenylisoquinoline], 2 [C∧N = 2-biphenyl-4-yl-quinoline], 3 [C∧N = 2-(fluoren-2-yl)-quinoline], 4 [C∧N = 2-dibenzofuran-3-yl-quinoline], 5 [C∧N = 2-dibenzothiophen-3-yl-quinoline], and 6 [C∧N = 2-phenanthren-2-yl-quinoline], have been investigated by density functional theory (DFT) and time-dependent DFT. They show a wide color tuning of photoluminescence from orange-red (λ = 601 nm) to saturated red (λ = 685 nm). The calculated absorption and emission properties of complexes 1 and 2 are in good agreement with the available experimental data. Complex 6 has the smallest ionization potentials (IP) value, which is consistent with its highest occupied molecular orbital energy level, and thus its hole injection is easiest. Corresponding to its lowest unoccupied molecular orbital energy level, the assumed complex 5 has the large electron affinities value and enhanced electron injection ability compared to the others. These calculated results show that the assumed complex 3 may possess better abilities than others and is the potential candidate for an efficient electrophosphorescent polymer-based red-emitting material. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Highlights: [•] Phosphorescence properties of five osmium(II) complexes have been investigated. [•] Calculated lowest energy emission of 3 is agreement with the experimental value. [•] Complex 5 has the best electron-transporting performance among these complexes. [Copyright &y& Elsevier]

We report a quantum chemical study of the electronic structures and spectral properties of three iridium(III) biscarbene complexes with different heteroleptic N^N ligands. The theoretical calculation reveals that the lowest-lying singlet absorptions at 434 nm for1and 487 nm for3are attributed to the mixed transition characters of metal-to-ligand charge transfer (MLCT) and ligand-to-ligand charge transfer (LLCT). However, for2, the lowest-lying singlet absorption at 509 nm is attributed to the MLCT. For1–3, the phosphorescence at 739, 913, and 737 nm are mainly attributed to3MLCT and3LLCT characters. For1and3, the emission energies are nearly the same, which is larger than that of2. Ionization potentials (IP) and electron affinities (EA) calculations show that the assumed complex3has large EA value and enhanced electron injection ability as compared to complexes1and2. Moreover, the reasons for different transition characters and phosphorescence quantum yield for the three complexes have been discussed in this paper. This theoretical contribution allows the factors determining the efficiency of radiative and nonradiative decay pathways in the three complexes. [ABSTRACT FROM PUBLISHER]

Abstract: We report a quantum-chemistry study of electronic structures and spectral properties of four Ir(III) complexes Ir[2-(2,4-di-X-phenyl)pyridine]2(picolinate), where X=–CH3 (1), –H (2), –CN (3), –NO2 (4). The absorption and emission spectra were calculated based on the optimized ground state and excited state geometries, respectively, by means of the time-dependent density functional theory (TDDFT). The effect from the electron-withdrawing and electron-donating substituents on charge injection, transport, absorption, and phosphorescent properties has been investigated. The absorption and emission properties can be altered by the different electron-withdrawing and electron-donating groups. Besides, ionization potential (IP), electron affinities (EA) and reorganization energy (λ hole/electron) 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. It can be anticipated that the complexes 3 and 4 have good charge transport rates and balance between the hole and electron. [Copyright &y& Elsevier]

Abstract: We report a quantum-chemistry analysis of four heteroleptic iridium(III) complexes (tfmppy)2Ir(tpip) [tfmppy=4-trifluoromethylphenylpyridine, tpip=tetraphenylimido-diphosphinate] (1), (tfmpyN3)2Ir(tpip) [tfmpyN3 =4-trifluoromethylphenyl-[1,2,3]-triazole] (2), (CN-pyN3)2Ir(tpip) [CN-pyN3 =4-cyanophenyl-[1,2,3]-triazole] (3) (ph-pta)2Ir(tpip) [ph-pta=2-(5-phenyl-[1,2,4]-triazol-3-yl)-pyridine] (4), which have been studied by using density functional theory (DFT) and time-dependent DFT (TDDFT) methods, to investigate their electronic structures, injection and transport properties, absorption and phosphorescence mechanism. The results reveal the different cyclometalated ligands have a large impact on the charge transfer performances of the studied complexes. The complex 4 possess better charge transfer abilities and balanced charge transfer rates, which is a potential candidate as blue-emitting material. [Copyright &y& Elsevier]

The electronic and photophysical properties of three blue cyclometalated Ir(III) complexes have been investigated by using the density functional theory (DFT) and time dependent density functional theory (TDDFT) methods. Both HOMO and LUMO values of complexes 1, 2 and 3 are in the order of 1 > 2 > 3. The lowest-lying singlet absorption for 1, 2 and three attributed to the configurations of the highest occupied molecular orbital (HOMO) to the lowest unoccupied molecular orbital (LUMO) with the d(Ir)+π(A)→π*(A) [MLCT/ILCT] character. Complexes 1, 2 and three possess almost the same phosphorescence wavelength and transition characters. [ABSTRACT FROM AUTHOR]

Various hazardous trace elements emitted from anthropogenic activities are attracting increasing public awareness. This study comprehensively explored the distribution and emissions of trace elements in coal-fired power plants (CFPPs) after ultra-low emission retrofitting by conducting field experiments, literature surveys, and model calculations. High levels of volatile Hg and semi-volatile As/Pb were mainly observed in fly ash and gypsum (96.6%–98.5%), while the proportion of non-volatile Cr in bottom ash was 9.23%. The Hg and As/Pb removal efficiencies were remarkably improved by ultra-low emission retrofitting, increasing by 5.67% and 2.08%/2.63%, respectively. However, ULE retrofitting only slightly affected (0.17%) non-volatile elements. These improvements were mainly attributed to the low-low-temperature electrostatic precipitator. Owing to the enhanced particle-capturing efficiencies, the concentrations of trace elements in the emitted gas of the tested CFPPs were low, ranging from 0.21–1.50 μg/m3, but accounted for a high proportion of the gas phase (61.8%–100%). Based on the national database of coal quality and their behaviour in CFPPs, we found that most of the concentrations of trace elements emitted from Chinese CFPPs were significantly lower than the internationally existing emission limits. However, owing to the skewed distribution characteristics of the emitted concentrations, we suggest issuing or revising the corresponding emission limits and improving the control of intense trace element pollution in China. Unlabelled Image • Volatile and semi-volatile elements enrich in fly ash and gypsum, while non-volatile element also distributes in bottom ash. • ULE retrofit significantly improves the removal of volatile element but have slight effect on non-volatile element. • Trace elements in the emitted gas of tested CFPPs present as high proportion of gas phase. • The skew distributions of the emitted concentrations of trace elements highlight the urgency to revise the emission standard. [ABSTRACT FROM AUTHOR]

• 300 training samples and 75 testing samples from seven sites in China were collected. • The combination of fatty acid profile and fatty acid δ13C fingerprinting was performed. • The combination of these two methods enhanced the prediction capability (100%). • The combination of two methods can be a promising tool for traceability of scallops. The aim of this study was to evaluate the combination of fatty acid profile and fatty acid δ13C fingerprinting to identify the origins of scallops. Fatty acid contents, as well as fatty acid δ13C values of 300 samples of three scallop species (Patinopecten yessoensis , Chlamys farreri , and Argopecten irradians) from seven sites in China were determined. Principal component analysis was performed on datasets to evaluate their performance of classification. Moreover, 75 samples were tested by discrimination analysis to estimate the accuracy of origin prediction. The results show that the accuracy rate of fatty acid profile and fatty acid δ13C fingerprinting for origin prediction was 92% and 85.3%, respectively. The combination of these two methods improved the identification, with an accuracy rate of 100.0%. These results indicate that the combination of fatty acid profile and fatty acid δ13C fingerprinting can be a precise and promising tool for origin traceability of scallops. [ABSTRACT FROM AUTHOR]