Effect Of Substituent Groups Research Articles

Design and exploration of 5-nitro-3-trinitromethyl-1H-1,2,4-triazole and its derivatives as energetic materials.

According to the fact that 5-nitro-3-trinitromethyl-1H-1,2,4 triazole (NTNMT) is a successful, good explosive, energetic groups such as -CH3, -NH2, -NHNO2, -NO2, -ONO2, -NF2, -CN, -NC, -N3 groups were introduced into NTNMT and their oxygen balance was at about zero. The energetic properties, detonation performance, and sensitivity were studied at the B3LYP/6-31G** level of density functional theory to seek for possible high energy density compounds. The effects of substituent groups on heat of formation (HOF), density ρ, detonation velocity D, detonation pressure P, detonation energy Q, and sensitivity (evaluated using oxygen balance OB, the nitro group charges -QNO2, and bond dissociation energies BDE were studied and discussed. The order of contribution of the substituent groups to ρ, D, and P was -NF2 > -ONO2 > -NO2 > -NHNO2 > -N3 > -NH2 > -NC > -CN > -CH3; while to HOF is -N3 > -NC > -CN > -NO2 > -NF2 > -ONO2 > -NH2 > -NHNO2 > -CH3. The trigger bonds in the pyrolysis process for NTNMT derivatives may be N-NO2, N-NH2, N-NHNO2, C-NO2, or O-NO2 varying with the attachment of different substituents. Results show that NTNMT-NHNO2, -NH2, -CN, and -NC derivatives have high detonation performance and good stability. In a word, the oxygen balance at about zero strategy in this work offers new routes for the improvement in properties and stabilities of energetic materials. In the present paper, several 5-nitro-3-trinitromethyl-1H-1,2,4 triazole (NTNMT) derivatives were designed. Their energetic properties, detonation performance, and sensitivity were studied at the B3LYP/6-31G** level of density functional theory (DFT) to seek for possible high energy density compounds (HEDCs). The different substituents have some changes in the influence on heat of formation (HOF), density ρ, detonation velocity D, detonation pressure P, detonation energy Q, and sensitivity. In a word, the oxygen balance at about zero strategy in this work offers new routes for the improvement in properties and stabilities of energetic materials.

ε-Caprolactone manufacture via efficient coupling Baeyer-Villiger oxidation with aerobic oxidation of alcohols

To avoid the use of peracids oxidant or highly concentrated hydrogen peroxide which is potentially hazardous and explosive, herein, a new route to ε-caprolactone was developed in which molecule oxygen was employed as the terminal oxidant. The commercial available N-hydroxyphthalimide and ammonium cerium nitrate were used as the key catalysts for the increased yield of ε-caprolactone. For instance, the selectivity of ε-caprolactone was obtained 92 % with 85 % conversion of cyclohexanone which was comparable to the strategies using highly concentrated hydrogen peroxide. The sacrificed alcohols were transformed into corresponding ketones which were also valuable chemicals. Furthermore, the efficiency of the alcohols was achieved to unprecedented 52 %. The Baeyer-Villiger oxidation of various other cycloalkanones was also examined. The substituent group effect on the efficiency of sacrificed alcohols was investigated in which weak electron-donating substituent induced nearly quantitative yield of ε-caprolactone. The reaction mechanism was studied with the help of electron paramagnetic resonance which indicated the existence of a radical pathway.

Differences in antioxidant potential of chalcones in human serum: In vitro study

IntroductionAn imbalance between oxidants and antioxidants in favour of oxidants, potentially leading to damage, is termed oxidative stress. Antioxidants (AO), either enzymatic or non-enzymatic, are the ones that can reduce diverse effects of pro-oxidants such as DNA, proteins and lipids damage. Chalcones (1,3-diaryl-2-propen-1-ones) are open chain flavonoids that are widely biosynthesized in plants. Aim of this study was to test antioxidative potency of 15 chalcones (Chs) in in vitro model in serum (native conditions), so as with exogenously induced oxidative stress. Material and methodsOxidative stress was induced in serum samples of healthy individuals with 0.25 mmol/L terc-buthyl-hydroperoxide (TBH), and then we monitored the effects of various concentrations of chalcones on oxidative stress parameters: total antioxidative status (TAS), total oxidative status (TOS), total concentration of sulfhydryl group (SHG) and prooxidative-antioxidative balance (PAB), and calculated prooxidative score, antioxidative score, and oxy score (OS). Nonparametric repeated measures ANOVA (Friedman's test) was used for comparison of antioxidative potency of samples with 15 different chalcones, in a native state and upon TBH influence. Spearman's nonparametric correlation analysis was used for estimation of relation between different parameters. ResultsNegative Oxy Score (OS) values for Chs11-15 showed significantly stronger antioxidative potency compared to other investigated chalcones (p < 0.05). Ch11, Ch13 and Ch14 remained with negative OS even after TBH addition, whereas OS of Ch12 and Ch15 became positive, with small nominal values. Samples with Ch11 and Ch13 showed significant negative correlation between TAS and TOS (p < 0.05 for both), but in Ch14 sample the negative correlation existed between TAS and PAB (p < 0.05). ConclusionLower value of OS (i.e. better antioxidative potency) was noticed in samples with Ch11-Ch15. Electron-donor effects of substituent groups as a structural part of these chalcones could explain its antioxidative capability. Phenolic and methyl groups are responsible for antioxidative ability enhancement of five chalcones with the best activity.

Novel Schiff-base derivatives and corresponding Eu(III) complexes: multiple-color, pH-responsive mechanism and fluorescence property

Abstract Great attention has been paid to synthesize organic ligands with good coordination ability to Eu(III) ion, however, in rare earth coordination field, it's still a challenge to prepare multifunctional organic ligands with good performance and potential application. In this work, we designed and synthesized novel methoxypicolinohydrazide Schiff-base derivatives (MPDS) and their corresponding Eu(III) complexes. Multiple-color emission in the solid state and pH response in alkaline environment of MPDS was investigated. The fluorescence intensity, color purity and fluorescence lifetime of Eu(III) complexes were studied by comparing different substituent groups. Density functional theory (DFT) calculations suggest that MPDS exhibit diverse fluorescence emission from green to orange due to the different electronegativity of substituent groups on the salicylaldehyde, and the maximum emission wavelengths are 512 nm, 534 nm and 582 nm, respectively. Besides, because of intramolecular charge transfer mechanism (ICT), MPDS exhibit the unique response to pH 7.0–12.0 by emitting green fluorescence in different linear ranges. All complexes emit excellent red fluorescence of Eu(III) ion with good thermal stability and high color purity. The effect of different substituent groups on fluorescence intensity and fluorescence lifetime of Eu(III) complexes is ordered: [EuL3 (NO3)3]·2H2O > [EuL1 (NO3)3]·2H2O > [EuL2 (NO3)3]·2H2O. Besides, the color purity of [EuL3 (NO3)3]·2H2O is 97.33%, which is the highest in all title Eu(III) complexes. These results indicate that [EuL3(NO3)3]·2H2O containing electron-donating substituent possesses the best fluorescence property. Based on the above results, both MPDS and Eu(III) complexes have a promising application prospect as luminescent functional material in the optical field.

Inhibitive and adsorption behavior of thiadiazole derivatives on carbon steel corrosion in CO2-saturated oilfield produced water: Effect of substituent group on efficiency

Three thiadiazole derivatives with different substituent groups, 2-(benzylthio)-5-methyl-1,3,4-thiadiazole(BMT), 2-(benzylthio)-5-(butylthio)-1,3,4-thiadiazole(BBT), and 5-(benzylthio)-1,3,4-thiadiazole-2-thiol(BTT), were synthesized and studied as the corrosion inhibitors for N80 carbon steel in CO2-saturated oilfield produced water. It is found that the synthesized thiadiazole derivatives could effectively inhibit the corrosion of N80 carbon steel by chemisorption. The corrosion inhibition performance of the organic compounds is in the order: BTT > BBT > BMT. The theoretical calculations indicate that the tautomeric transformation from thiol-BTT to thione-BTT may be responsible for the high inhibition performance of BTT.

Two Series of Substituent‐Group‐Directed Adipate‐Based Lanthanide Coordination Polymers: Syntheses, Structures, Photoluminescence, and Magnetism

Two series of lanthanide‐organic coordination polymers (CPs) [Ln2(L1)3(H2O)4] [Ln = Nd (1), Sm (2), Eu (3), Gd (4), Tb (5), and Dy (6), H2L1 = 3‐methyl‐adipic acid] and [Ln4(L2)6(H2O)4] [Ln = Nd (7), Sm (8), Eu (9), Gd (10), Tb (11), and Dy (12), H2L2 = 3‐tert‐butyl‐adipic acid] have been synthesized by the solvothermal reactions of lanthanide salts with two types of flexible substituent adipates. All of these CPs were characterized by single‐crystal X‐ray diffraction, elemental analysis, IR spectroscopy, powder X‐ray diffraction, and thermal analysis. Structural analyses reveal that CPs 1–6 and 7–12 are isostructural, respectively. CPs 1–6 show a two‐dimensional (2D) layer constructed from the 3‐methyl‐adipate anions bridging two types of binuclear Ln2 units. The adjacent 2D layers are further extended into a three‐dimensional (3D) supramolecular framework through the hydrogen‐bonding interactions. CPs 7–12 also exhibit a 2D structure. The carboxyl groups of 3‐tert‐butyl‐adipate link four types of TbIII ions to form a one‐dimensional (1D) inorganic TbIII chain. The neighboring 1D inorganic TbIII chains are further connected by the 3‐tert‐butyl‐adipate anions to construct a 2D network. The effect of substituent groups on the formation of adipate‐based lanthanide CPs as well as the photoluminescence and magnetic properties of 1–12 were investigated in detail.

Fundamental properties of TEMPO-based catholytes for aqueous redox flow batteries: effects of substituent groups and electrolytes on electrochemical properties, solubilities and battery performance.

Water-soluble 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) derivatives have been frequently utilized as catholytes for aqueous redox flow batteries to achieve cost-effective renewable energy storage. However, fundamental knowledge of TEMPO derivatives is still largely underdeveloped. Herein, a comprehensive study on the properties of TEMPO derivatives has been conducted in aqueous electrolytes. The results confirm that the redox potential, diffusion coefficient, electron transfer rate constant and solubility are clearly influenced by functional groups of TEMPO derivatives and supporting electrolytes. The charge–discharge cycling performance is evaluated using a symmetric redox flow battery configuration. The capacity decay for TEMPO-based catholytes is mainly derived from the crossover of the oxidized state. The presented study not only advances an in-depth understanding of TEMPO-based RFB applications, but also highlights the challenge of crossover of redox-active TEMPO derivative molecules applied in aqueous RFBs.

Effects of substituent groups on the crystal structures and anti-cervical cancer activity of zero-/two-dimensional Cu(II) complexes

In this study, two similar substituted imidazo[1,2-a]pyridine ligands with different coordination groups are facilely synthesized and further used for constructing two novel Cu(II)-based coordination complexes [CuCl2(L1)2] (1, L1 = 3-(imidazo[1,2-a]pyridin-3-yl)-1-(pyridin-3-yl)propan-1-one) and [Cu(L2)2]n (2, L2 = 4-(imidazo[1,2-a]pyridin-2-yl)-2-oxobutanoic acid) via a one-pot solvothermal reaction. Then the activity of the synthesized complexes is assessed against HeLa cervical cancer cells with the CCK-8 method. The results indicate that complex 1 has an excellent inhibitory effect on cancer cell proliferation, migration, and invasion capabi­lity. Moreover, a further study is performed and it reveals the mechanism of complex 1, which exerts the anti-cancer ability via inducing the HeLa apoptotic cell death. Above all, synthesized complex 1 has an outstanding in vitro antitumor activity.

RETRACTED ARTICLE: Effects of Substituent Groups on the Crystal Structures and Anti-Cervical Cancer Activity of Zero-/Two-Dimensional Cu(II) Complexes

In this study, two similar substituted imidazo[1,2-a]pyridine ligands with different coordination groups are facilely synthesized and further used for constructing two novel Cu(II)-based coordination complexes [CuCl2(L1)2] (1, L1 = 3-(imidazo[1,2-a]pyridin-3-yl)-1-(pyridin-3-yl)propan-1-one) and [Cu(L2)2]n (2, L2 = 4-(imidazo[1,2-a]pyridin-2-yl)-2-oxobutanoic acid) via a one-pot solvothermal reaction. Then the activity of the synthesized complexes is assessed against HeLa cervical cancer cells with the CCK-8 method. The results indicate that complex 1 has an excellent inhibitory effect on cancer cell proliferation, migration, and invasion capability. Moreover, a further study is performed and it reveals the mechanism of complex 1, which exerts the anti-cancer ability via inducing the HeLa apoptotic cell death. Above all, synthesized complex 1 has an outstanding in vitro antitumor activity.

Substituent group-tunable hydrogen evolution activity observed in isostructural Cu(ii)-based coordination polymer photocatalysts.

Elucidations on the structure-activity correlations of non-Pt coordination polymer (CP)-based photocatalysts are highly significant for both the enhancement in catalytic activity and large-scale industrial applications of sustainable hydrogen from water splitting. Herein, three isostructural [Cu(HL)2(R-BDC)]n (denoted as Cu-CP-R, HL = 4'-(4-hydroxyphenyl)-4,2':6',4''-terpyridine, R-BDC = 2-R-1,4-benzenedicarboxylate, R = NO2, OH and Br) CPs were solvothermally synthesized by varying the substituents attached to benzenedicarboxylate, which together with two previously reported analogues (R = NH2 and H) were used as photocatalysts to systematically explore the substitution effect on the hydrogen evolution activity. These five CPs feature isomorphic layered motifs with axially elongated CuII octahedra extended alternately by ditopic HL and R-BDC2- connectors, in which R behaves structurally as a non-coordinate group. The hydrogen production rate over the Cu-CP-R photocatalysts increased from 0.21 to 2.34 mmol g-1 h-1, which followed the order of -NH2 > -NO2 > -H > -OH > -Br. Furthermore, the combined experimental and theoretical investigations reveal that the free R moiety significantly dominates the photocatalytic activity by shifting the d states of the CuII ion towards the Fermi level, controlling the potential of the conduction band and quickening the charge transfer ability. These important findings can provide informative hints for the design of high-performance, earth-abundant non-noble metal CP-based semi-conductive photocatalysts.

Printable UV-Light Sensor for Human Eye Protection.

Light-emitting diode based electronic screens emit near-ultraviolet radiation, which causes harm to the human eye after prolonged exposure. Thus, it is of paramount importance to prepare a sensitive and adjustable visible near-ultraviolet sensor for retinal warning. Herein, a series of bipyridine derivatives were synthesized to investigate effects of substituent groups and anions on photochromic properties via both experimental and theoretical studies. The introduction of dual hydrogen bonding urea onto substituted groups significantly accelerated the photochromic rate due to strong intermolecular interactions, which reduces molecular spacing and promotes the electron-transfer effect. Moreover, the photochromic rate was tuned by changing the size of the anion. Larger anions widen the molecular spacing and weaken the electron transfer and eventually lead to a decrease in the photochromic rate. Finally, bipyridine derivatives were printed on a polyethylene terephthalate film or paper as a sensitive, adjustable, and visible sensor to monitor near-ultraviolet radiation emitted by an light-emitting diode screen.

“AIE+ESIPT” bis Schiff-base ligands with multicolor emission and their corresponding Eu(III) complexes: Synthesis and properties research

A series of bis Schiff-base ligands and their corresponding Eu(III) complexes were synthesized easily and characterized by 1H NMR,13C NMR, ESI-MS+, Elemental analysis, Molar conductivity, Thermogravimetric analysis. The AIE characteristics of all ligands (L1−4) were investigated, fluorescence and electrochemical properties of Eu(III) complexes (EuL1−4Cl3·2H2O) were also studied. The results indicate that all ligands not only possess AIE characteristics, but exhibit diverse fluorescence emission from orange to green (the emission peaks are 588 nm, 556 nm, 548 nm and 520 nm, respectively). All complexes show characteristic red fluorescence of Eu (III) ion. The effect of various substituent groups on fluorescence intensity of complexes is ordered: –N(CH2CH3)2>-OCH3>-OH > -Cl and EuL4Cl3·2H2O emits the strongest fluorescence. The results of electrochemical properties demonstrate that electron-donating groups increase the HOMO energy level and LUMO energy level of complexes, but the electron-withdrawing groups behaves contrarily. Based on the above results, all ligands and their corresponding Eu(III) complexes are promising materials in the field of optics.

Stimuli-responsive aggregation-induced fluorescence in a series of biphenyl-based Knoevenagel products: effects of substituent active methylene groups on π-π interactions.

A series of three biphenyl-based Knoevenagel products (denoted 1a, 1b, 1c) with active methylene groups has been synthesized. Compounds 1a and 1b show strong solid-state fluorescence, whereas 1c displays low emission. Effects of substituent groups in condensed phase packing of the molecules have been investigated and correlated with their photophysical properties. Interestingly, compound 1a exhibits mechanofluorochromism with emission color changes from yellow to green (wavelength shift of 40 nm) after mechanical grinding. Furthermore, fluorescence of 1a and 1b is turned off under alkaline conditions, making them potential candidates for aggregation-enhanced emission-based pH sensors.

Metalloporphyrin as a Biomimetic Catalyst for the Catalytic Oxidative Degradation of Lignin to Produce Aromatic Monomers

Lignin, an abundant biomass waste, was degraded under microwave irradiation with H2O2 as the oxidant and metalloporphyrin as the catalyst. The effect of substituent group (4-methylphenyl, 4-methoxyphenyl, 4-bromophenyl and 4-carboxyphenyl) at the meso-benzene ring of metalloporphyrin, central metal ion (Co, Mn, Ni and Fe) and axial ligand (chlorine, p-hydroxypyridine, p-pyridinecarboxaldehyde) on the degradation of lignin was investigated. The electron-withdrawing group not only reduces the electron cloud density on the porphyrin ring, but also promotes the formation of higher active intermediate [(Porp)MeIV=O]+·. Therefore, the presence of stronger electron-withdrawing substituents makes the metalloporphyrins more efficient in lignin degradation. Compared to Co porphyrin, there are less amount of [(Porp)MeIV=O]+· formed when Mn, Fe or Ni porphyrin was used as the catalyst for degrading lignin. Consequently, Co porphyrin contributed to a higher YAM (the yield of aromatic monomers). The strong nucleophilicity and the low steric hinderance of axial ligand was advantageous for the stability of metalloporphyrins, which is favorable for improving the catalytic activity to the degradation of lignin. It is found that the YAM increases 20.1% from 5.6% by using CoTBrPPCl as the reaction catalyst under the optimized conditions

Terminal group modification of alkylthio substituted small molecule donor materials for organic solar cells

Side chains and terminal groups have an important effect on photovoltaic performance of organic solar cells (OSCs) based on oligothiophene donor materials. In order to study the effect of alkylthio substituent and different terminal groups on photovoltaic properties, a series of small molecules were designed and synthesized. Molecule LS0 was modified by alkyl as side chains and 2-ethylrhodanine as terminal groups while LS1a, LS1b, LS2, LS3 were substituted with alkylthio side chains and capped with different terminal groups of 2-ethylrhodanine, 2-hexylrhodanine, 2-ethylhexyl cyanoacetate, and 1,3-indanedione, respectively. Compared with LS0, alkylthio substituted LS1a exhibited higher HOMO and LUMO due to more planar backbone. Capped with different terminal groups, LS1a, LS1b, LS2, and LS3 showed the different optical and photovoltaic properties. Among these molecules, OSCs based on LS1b showed the highest power conversion efficiency (PCE) of 8.38% while others showed PCE of 7.87%, 6.52%, 6.52%, and 4.65% for LS0, LS1a, LS2, and LS3, respectively. The results demonstrated that rational selecting side chains and terminal groups could be a promising strategy to promote the performance of small molecule-based OSCs.

Structure-activity relationship study of thiazolyl-hydroxamate derivatives as selective histone deacetylase 6 inhibitors

Several human diseases are associated with aberrant epigenetic pathways mediated by histone deacetylases (HDACs), especially HDAC6, a class IIb HDACs, which has emerged as an attractive target for neurodegenerative and autoimmune disease therapeutics. In a previous study, we developed the novel HDAC6-selective inhibitor 9a ((E)-N-hydroxy-4-(2-styrylthiazol-4-yl)butanamide) and showed that it has anti-sepsis activity in vivo. In this study, we conducted structure-activity relationship (SAR) studies to optimize the activity and selectivity of HDAC6, synthesizing its derivatives with various aliphatic linker sizes and cap structures. We identified 6u ((E)-N-hydroxy-3-(2-(4-fluorostyryl)thiazol-4-yl)propanamide), which has nanomolar inhibition activity and a 126-fold selectivity for HDAC6 over HDAC1. Through the docking analyses of 6u against HDAC subtypes, we revealed the importance of the optimal aliphatic linker size, as well as the electronic substituent effect and rigidity of the aryl cap group. Thus, we suggest a new rationale for the design of HDAC6-selective inhibitors.

Theoretical Design of Near-Infrared Fluorescent Sensor for F Anion Detection Based on 10-Hydroxybenzo[h]quinoline Backbone.

Proper design and development of near-infrared (NIR) fluorescent sensors is very important for applications in vivo. In this work, we theoretically designed a ratiometric and NIR fluorescent sensor based on the 10-hydroxybenzo[h]quinoline (HBQ) backbone via systematically investigating the substituent effects of electron-donating groups (−NH2, −CH3, −C(CH3)3) and electron-withdrawing groups (−NO2, −CN, −F, −Cl, −CF3) at the proton donor site on the proton transfer process in HBQ in both the S0 and the S1 states. According to the calculated potential energy profiles along the proton transfer as well as the photophysical properties among all the derivatives, we successfully screened out that 7NH2-HBQ is a promising fluorescent sensor exhibiting the near IR emission spectra accompanied by the large Stokes shift. The potential use of 7NH2-HBQ for F– detection among anions (F–, Cl–, and Br–) was further studied, and the results showed that 7NH2-HBQ is very sensitive and selective toward F– based on the intermolecular hydrogen bonding interaction between F– and OH bond, forming a new complex FACS0. The ratiometric change in the fluorescence intensity could be induced by the H–F bond transfer from the O atom to the N atom in the S1 state.

Tuning the aqueous solubility, chemical reactivity and absorption wavelength of azo dye through systematic adjustment of molecular charge density: a DFT study

ABSTRACT Effects of substituent groups on aqueous solubility, chemical reactivity and absorption wavelength of Disperse red 73 (DR73) were theoretically investigated using density functional theory (DFT) method. This study is in view of introducing new monoazo disperse dyes with improved aqueous solubility, absorption behaviour, and degradation tendency. Aqueous solubility was calculated using Cramer et al. solubility equation and the parameters used were obtained using conductor-like screening model for realistic solvation (COSMO-RS). Chemical reactivity and catalytic affinity were evaluated using some molecular orbital dependent reactivity descriptors. Susceptibility of the molecules to radical attacks was predicted using Fukui functions. Absorption wavelength was calculated using the B3LYP functional with the 6-31G* basis set. The results showed that electron withdrawing −CN substituent promoted aqueous solubility of DR73 more than the −NO2 counterpart, while the solubility is mostly enhanced by −NH2 substituent compared to the other electron donating groups studied. Most of the derivatives yielded longer absorption wavelength in the visible region and are chemically less stable (i.e. more degradable) compared to the parent molecule. Among the photocatalysts considered, ZnO is predicted as the most efficient candidate for degradation of the dyes. Predicted properties showed remarkable sensitivity to substitution positions in the parent molecule.

Yellow-to-blue switching of indole[3,2-b]carbazole-based electrochromic polymers and the corresponding electrochromic devices with outstanding photopic contrast, fast switching speed, and satisfactory cycling stability

Three novel π-conjugated indolo[3,2-b]carbazole derivatives, 2,8-di(thiophen-2-yl)-5,11-dioctyl-indolo[3,2-b] carbazole (TICZ), 2,8-bis(4-ethylthiophen-2-yl)-5,11-dioctyl-indolo[3,2-b]carbazole (ETICZ) and 2,8-bis(2-(3,4-ethylenedioxythiophene))-5,11-dioctyl-indolo[3,2-b]carbazole (EDTICZ), were synthesized and electrochemically polymerized to afford the corresponding polymers. The effects of different substituent groups on thiophen units in terms of optical, electrochemical, and electrochromic properties and the performance of electrochromic devices (ECDs) were investigated in detail. Electrochemical and optical analysis demonstrated that incorporation of strong auxochromic groups resulted in polymer PEDTICZ with low oxidation potentials, red-shifted absorption peaks and corresponding narrow band gap values but is unfavorable for incorporating ethyl groups. Spectroelectrochemical studies indicated an evident variation in the absorption spectra as well as significant color changes for all of the polymer films upon application of an external potential. PTICZ had high optical contrast with visible light (58.6%), fast switching speed (0.92 s), and satisfactory coloration efficiency (167 cm2 C−1). Of these three systems, the results for PEDTICZ were next best, and those for PETICZ were third. Also, there was a larger contrast (82.7% and 57.8%) in the NIR region (1500 nm) for the PTICZ and PEDTICZ films, respectively. Along with high coloring efficiencies, these results indicate that these systems are favorable for many NIR applications.

The effects of substituted picolinate ligands on the photophysical and electrochemiluminescence properties of bis-cylcometalated iridium(III) complexes

The bicyclometalated iridium(III) complexes bearing 2,4-diphenylquinoline with fluorinated picolinates and methoxy picolinates as ancillary ligands were synthesized, and the effects of substituent groups at the ancillary ligands on the photophysical and electrochemiluminescent properties of the cyclometalated iridium(III) complexes were also investigated. The cyclometalated iridium(III) complexes with methoxy picolinates were obtained by a tandem reaction under a mild condition. All these complexes display the intense orange phosphorescence with the peak wavelengths at 586–600 nm. It is significant to note that the 6-position substitution of picolinates reduces the stability of the cyclometalated iridium(III) complexes, and the luminous and electrochemiluminescence (ECL) efficiency is accordingly reduced. Electrochemical testing suggested that the low oxidation potential could be beneficial to improve ECL efficiency. Moreover, the electron-donating methoxy group may result in the increase of photoluminescence (PL) and ECL efficiencies of the iridium(III) complexes, whereas the electron-withdrawing fluorine groups may lead to reducing of both PL and ECL efficiencies. Especially, the ECL intensity of the cyclometalated iridium(III) complex with 3,5-dimethoxy picolinate is ca. 11 times higher than that of the typical [Ru(bpy)3]2+(bpy = 2,2′-bipyridine).The ECL intensity of complex MeOIr4 is 11 times higher than that of the typical [Ru(bpy)3]2+.