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Herein, we report various metal complexes containing {5-(2-hydroxy)phenyl}tetrazolyl (H 2 hptz ) which form various high-dimensional coordination polymers in a crystalline solid state. A reaction of metal perchlorates, 2,2′-bipyrimidine ( bpym ), KOH, and tetrazolyl ligand (H 2 hptz ) in H 2 O or N , N -dimethylmethanamide (DMF) yield 2-D [Cu( hptz )( bpym )] n ( 1 ), [Zn( hptz )( bpym )] n ( 2 ) and 3-D [K( bpym ) 2 Ni( hptz )(H 2 O) 2.5 (OH)] n ( 3 ) coordination complexes with a high synthetic yield. These compounds were characterized by elemental analysis, IR spectroscopy, and single crystal X-ray crystallography. Cu 2+ and Zn 2+ complexes showed 2-D infinite network systems, forming coordination polymers (caused by extra bonding between metal ions and tetrazolyl). The environment of the Cu and Zn metal centers are quite similar; however, Zn 2+ complexes have significantly shorter Zn–O bond distances with the hydroxyl group of other [Zn( hptz )( bpym )] unit. The Ni 2+ complex 3 showed a completely different composition from that of complexes 1 – 2 . Complex 3 showed 3-D structure based on octahedral units, which were composed of two hptz 2− and one bpym ligands around the Ni center. These units infinitely repeat with K ions and water molecules along the a -, b -, and c -axes of the unit cells. Their magnetic behaviors were also studied. [ABSTRACT FROM AUTHOR]

Tetradentate Pt(II) complex (Pt‐Trz)‐sensitized green fluorescent organic light‐emitting‐diodes (OLEDs) are developed to improve the external quantum efficiency (EQE) of a green fluorescent emitter (PhtBuPAD). Pt(II) complex and a green fluorescent emitter with bulky blocking units are chosen to efficiently manage energy transfer in phosphor‐sensitized OLEDs. The Pt‐Trz phosphor‐sensitized fluorescent OLED with 2 wt% PhtBuPAD exhibits high EQE of 24.2% and maintains high EQE of 23.4% at a luminance of 3000 cd m−2, realizing low efficiency roll‐off of 3.8%. Moreover, high EQE is achieved even at a high PhtBuPAD‐doping concentration of 3 wt%. In addition, the 2 wt% PhtBuPAD‐doped phosphor‐sensitized device achieves high maximum power efficiency of 91.1 lm W−1, one of the highest power efficiencies among existing green sensitized devices. This study demonstrates that Pt‐Trz phosphor‐sensitized devices with an excellent triplet exciton utilization ability can achieve high EQE, low efficiency roll‐off, and weak doping concentration quenching simultaneously. [ABSTRACT FROM AUTHOR]

A series of mono-, di-, and triphosphonium-substitutedtriarylboranes,[Mes2BArP]I ([2]I), [MesBArP2]I2([3]I2), and [BArP3]I3([4]I3)(ArP= 4-(MePh2P)-2,6-Me2-C6H2), were prepared from the correspondingneutral boranes 2a–4a. The crystalstructure of [4]I3determined by X-ray diffractionstudy revealsperipheral decoration of aryl groups with phosphonium moieties. Theanion affinity of the cationic boranes for fluoride and cyanide ionswas investigated by UV–vis absorption titrations in aqueoussolution. The triarylboranes, [2]I–[4]I3bind both fluoride and cyanide ions in a DMSO/H2O (7:3 v/v) mixture with high binding constants (K). Comparison of the Kvalues of triarylboranesfor fluoride reveals that fluorophilicity increases with the increasingnumber of phosphonium moieties: [2]+(K= 2.3 × 101M–1) <[3]2+(3.6 × 105M–1) < [4]3+(1.0 × 107M–1). A similar trend is also observed in the cyanidebinding, with Kvalues that are greater by 2–4orders of magnitude than those in the fluoride binding. These resultsindicate an apparent additive effect of multiple phosphonium substitutionson the Lewis acidity enhancement of triarylboranes. The triphosphoniumborane [4]Cl3, a water-soluble form of [4]I3, was further utilized in evaluating the anionaffinity in water. While [4]3+is shown tohardly bind fluoride in buffered water at pH 7, it binds cyanide witha high binding constant (1.7 × 107M–1). [ABSTRACT FROM AUTHOR]

A novel rechargeable meso-aryl Bodipy-based Cys sensing ensemble has been developed (“turn on,”ΦF = ＜0.05 → 0.72, limit of detection = 6.0 × 10−6 M) with exceptional selectivity over homocysteine, N-acetylcysteine, glutathione (GSH) and methionine. [ABSTRACT FROM AUTHOR]

Abstract: A cationic triarylborane Lewis acid bearing benzothiazolium moiety, 2-(4′-dimesitylborylphenyl)-3-methylbenzo[d]thiazol-3-ium ([2]+) was prepared from a neutral borane (2a) and their crystal structures were determined from X-ray diffraction studies. While 2a shows a blue-shift with a small decrease in the UV–vis absorption band upon fluoride binding to the boron atom, [2]+ undergoes a red-shift of the absorption band which tails over visible region, giving rise to the color change of the solution from colorless to yellow. The fluoride binding constant in THF/H2O (9/1, v/v) is calculated to be 1.3 × 104 M−1 that is much greater than that of a neutral borane 2a (K = 4.2 × 102 M−1). DFT calculation results suggest that the absorption process in the fluoroborate (2F) is involved with π(Mes)→π*(phenylbenzothiazolium) intramolecular charge transfer and the greater elevation of the π(Mes) donor level is responsible for the turn-on colorimetric response of [2]+. [Copyright &y& Elsevier]

Nickel monocarbonyl species with Ni(I) and Ni(0) have been synthesized and fully characterized by employing an acriPNP-Ph pincer ligand having a –C(Ph)2– bridge moiety to tether two aromatic rings. To see the effect of the bridge moiety, these complexes were structurally compared with the previously studied nickel complexes supported by PNP and acriPNP-Me ligands and methylation of the nickel carbonyl species was particularly investigated. Since a Ni(I)–CO species is known to be one of the key intermediates during the C–C coupling reaction to give an acetyl species, according to the paramagnetic mechanism of acetyl coenzyme A synthase (ACS), their reactivity toward MeI has been examined. Methylation of a nickel(I)–CO species reveals enhanced C–C coupling when both acriPNP-Me and acriPNP-Ph ligands were used. According to spin density analysis calculated by density functional theory, all Ni(I)–CO species reveal similar spin density at nickel and the carbon atom of CO. X-ray crystallographic data suggest that the corresponding selectivity may be related to the steric influence. For both (acriPNP-Ph)Ni–CO (2) and (acriPNP-Me)Ni–CO (2′), the nickel(I) site is sterically well protected, leading to selective interaction with a methyl radical to give a nickel acyl product. Steric influence was marginally observed when an anionic {(acriPNP-R)Ni–CO}− (R = Me or Ph) species reacted with MeI. The corresponding C–C coupled product was also observed from the methylation of nickel(0)–CO species. [ABSTRACT FROM AUTHOR]

The tetradentate ligand, merging a carbazole unit with high triplet energy and dimethoxy bipyridine, renowned for its exceptional quantum efficiency in coordination with metals like Pt, is expected to demonstrate remarkable luminescent properties. However, instances of tetradentate ligands such as bipyridine-based pyridylcarbazole derivatives remain exceptionally scarce in the current literature. In this study, we developed a tetradentate ligand based on carbazole and 2,3′-bipyridine and successfully complexed it with Pt(II) ions. This novel compound (1) serves as a sky-blue phosphorescent material for use in light-emitting diodes. Based on single-crystal X-ray analysis, compound 1 has a distorted square-planar geometry with a 5/6/6 backbone around the Pt(II) core. Bright sky-blue emissions were observed at 488 and 516 nm with photoluminescent quantum yields of 34% and a luminescent lifetime of 2.6 μs. TD-DFT calculations for 1 revealed that the electronic transition was mostly attributed to the ligand-centered (LC) charge transfer transition with a small contribution from the metal-to-ligand charge transfer transition (MLCT, ~14%). A phosphorescent organic light-emitting device was successfully fabricated using this material as a dopant, along with 3′-di(9H-carbazol-9-yl)-1,1′-biphenyl (mCBP) and 9-(3′-carbazol-9-yl-5-cyano-biphenyl-3-yl)-9H-carbazole-3-carbonitrile (CNmCBPCN) as mixed hosts. A maximum quantum efficiency of 5.2% and a current efficiency of 15.5 cd/A were obtained at a doping level of 5%. [ABSTRACT FROM AUTHOR]

Efficient, electrochemically stable blue phosphors are essential for advancing the organic light‐emitting diode (OLED) industry. Specifically, the characteristics of these phosphors must be further refined to realize commercially viable OLED devices with high stability, efficiency, and color purity. To that end, a new simple molecular design approach is devised in this study for synthesizing tetradentate‐ligand‐based Pt(II) complexes exhibiting intense blue emission. Essentially, novel Pt(II) complexes Pt3 and Pt4 are prepared by introducing the tert‐butyl and cyano groups to the ligand of previously reported highly stable, efficient Pt(II) complexes for preventing molecular aggregation and regulating the frontier levels, respectively, and then fully characterized. Both complexes display a blue emission band in solution and solid states with remarkably low full‐width‐at‐half‐maximum values. Additionally, multilayer phosphorescent OLEDs are fabricated using Pt3 or Pt4 as emitters and SiCzCz/SiTrzCz2 as a mixed‐host system. The devices demonstrate outstanding performance parameters, such as higher efficiencies than those of the devices containing the previously reported Pt(II) complexes and good color purity (CIEy ≈ 0.18). These findings suggest that the molecular design approach employed in this study for creating tetradentate‐ligand‐based Pt(II) blue phosphors is effective and can potentially expedite the commercialization of blue phosphorescent emitters in the OLED industry. [ABSTRACT FROM AUTHOR]

A novel fluorescent difluoroboroazaoxobenzazulene dye has been synthesized from commercially available substrates in “one pot”; it was characterized structurally and spectroscopically, derivatized and finally compared to a related BODIPY system that demonstrates “turn-on” H+(42-fold) and F−(∼5-fold) responses. [ABSTRACT FROM AUTHOR]

In this study, we introduce two ortho‐carboranyl compounds, namely ICzCB and mTPCB, which exhibit different planarity in their appended π‐conjugated aromatic groups, to investigate the influence of geometric effects on the regulation of the radiative efficiency. Both the compounds are fully characterized, revealing distinct geometric differences (planarity) in their single‐crystal structures. While ICzCB presents strong ICT‐based emission in the solid (film) state, mTPCB displays dual emission in the high‐ and low‐energy regions that originates from locally excited (LE)‐ and ICT‐based processes, respectively. Quantitative analysis of the photophysical characteristics of the compounds shows that the ICT‐based radiative efficiency in ICzCB is higher than that in mTPCB. Consequently, these findings demonstrate that the planarity of the π‐conjugated aryl group appended on o‐carborane, which is represented by planar ICzCB and distorted mTPCB, is an important key to control the ICT‐based radiative decay efficiency. [ABSTRACT FROM AUTHOR]

Herein, we prepared an o-carborane compound (9biAT) linked to a 9,9′-bianthracene moiety at each C9-position. The compound exhibited reddish emission in solid and solution states. The solvatochromism effect and theoretical calculation results for the excited (S1) state of 9biAT verified that the emission was attributed to ICT transition. In particular, the structural rigidity and the orthogonal geometry around the carborane enhanced ICT-based emission in the solution state at 298 K, resulting in a considerably high quantum efficiency (Φem = 86%) in cyclohexane. In addition, both the Φem value and radiative decay constant (kr) gradually decreased with an increase in the polarity of the organic solvent. Theoretical modelling of the charge distribution in the S1-optimised geometry revealed that charge recombination in the radiative-relaxation process upon ICT transition could be delayed under polar conditions. Consequently, a high Φem value in the solution state at room temperature can be obtained by maintaining molecular rigidity and controlling the polarity of the environment. [ABSTRACT FROM AUTHOR]

Herein, p -terphenyl-based o -carboranyl compounds, 4,4″-bis[2-( p - n -butylphenyl)-1- o -carboran-1-yl]- p -terphenyl ( 1 ) and 4,4″-bis(2- n -butyl-1- o -carboran-1-yl)- p -terphenyl ( 2 ), were prepared and fully characterized by multinuclear NMR spectroscopy and elemental analysis. The molecular structure of 1 was also analyzed by single-crystal X-ray diffraction method. Both compounds showed a dual emission band ( λ em ∼ 350 and 450 nm) in the rigid state (e.g., solution at 77 K), in contrast with a single emission peak at ca. 350 nm observed in solution at ambient temperature. Theoretical calculations on the first excited singlet state of each compound suggested that emission in the low-energy region distinctly involved intramolecular charge transfer (ICT) between carborane and terphenylene rings of both compounds; however, the high-energy emission of 1 was correlated with ICT between carborane and terminal phenyl rings, while that of 2 involved ICT between carborane and terphenylene as well as a π → π ∗ transition of the terphenylene moiety. Thus, it was concluded that the absence of terminal phenyl rings in o -carboranyl compounds leads to a π → π ∗ transition-based emissive band. The quantum efficiency and radiative decay values of 2, which are not drastically enhanced in the rigid state compared to the solution state at ambient temperature, also showed that the emission band of 2 is not perfectly correlated with the charge transfer (CT) transition band, in contrast to the case of 1 . [ABSTRACT FROM AUTHOR]

Although the remarkable growth of the organic light‐emitting diode (OLED) industry has occurred via continuous, extensive efforts toward the utilization of various organometallic luminophores as phosphorescent emitters, the development of blue phosphorescent emitters with improved efficiencies and high electrochemical stabilities is essential. To this end, herein the preparation of two novel tetradentate Pt(II) complexes, Pt1 and Pt2, and their application as blue phosphorescent emitters in OLED devices is described. Both complexes exhibit intense bluish emission in the solution and solid states. In addition, these complexes display very high phosphorescent quantum efficiencies (>89%) with host materials and thermal stabilities (>390 °C). Multilayer phosphorescent OLEDs containing Pt1 or Pt2 as emitters with mCBP/CNmCBP‐CN mixed‐host systems are fabricated. The devices exhibit outstanding performances, including high current, power, external efficiencies, and potential device lifetime in addition to sky‐blue (Pt1) or blue (Pt2) electroluminescence. These results clearly suggest that these tetradentate Pt(II) dopants are promising candidates as highly efficient, stable blue phosphorescent emitters in OLEDs. [ABSTRACT FROM AUTHOR]

The efficiency of intramolecular charge transfer (ICT)-based emission on π-aromatic-group-appended closo-ortho-carboranyl luminophores is known to be affected by structural fluctuations and molecular geometry, but investigation of this relationship has been in progress to date. In this study, four naphthyl-based bis-o-carboranyl compounds, in which hydrogen (15CH and 26CH) or trimethysilyl groups (15CS and 26CS) were appended at the o-carborane cage, were synthesized and fully characterized. All the compounds barely displayed an emissive trace in solution at 298 K; however, 15CH and 26CH distinctly exhibited a dual emissive pattern in rigid states (in solution at 77 K and in films), attributed to locally excited (LE) and ICT-based emission, while 15CS and 26CS showed strong ICT-based greenish emission. Intriguingly, the molecular structures of the four compounds, analyzed by single X-ray crystallography, showed that the C-C bond axis of the o-carborane cage in the trimethysilyl group-appended compounds 15CS and 26CS were more orthogonal to the plane of the appended naphthyl group than those in 15CH and 26CH. These features indicate that 15CS and 26CS present an efficient ICT transition based on strong exo-π-interaction, resulting in a higher quantum efficiency (Φem) for ICT-based radiative decay than those of 15CH and 26CH. Moreover, the 26CS structure revealed most orthogonal geometry, resulting in the highest Φem and lowest knr values for the ICT-based emission. Consequently, all the findings verified that efficient ICT-based radiative decay of aromatic group-appended o-carboranyl luminophores could be achieved by the formation of a specific geometry between the o-carborane cage and the aromatic plane. [ABSTRACT FROM AUTHOR]

A series of 4‐NEt2‐appended salen−indium complexes bridged by different diimine units (ethylene [Et, 1], phenylene [Ph, 2], and benzonitrile [PhCN, 3]) with different electronic effects were prepared in high yields by a one‐pot synthetic procedure. Among them, the solid‐state structure of 1 was identified by X‐ray crystallography, featuring a square‐pyramidal structure around the indium center. Ultraviolet–visible (UV/Vis) absorption and emission spectra of 1–3 showed typical ππ* electronic transitions centered on the salen ligands, which underwent gradual redshifts as the electron‐withdrawing ability of the bridging units increased. Such bathochromic shifts resulted from lowering the energy levels of the lowest unoccupied molecular orbital (LUMO). In addition, the full width at half maxima for the emissions of 1–4 gradually decreased with increasing electron‐accepting property of the bridging units. The observed photophysical properties were further supported by theoretical calculations. [ABSTRACT FROM AUTHOR]

In this study, we present a strategic methodology for molecular design aimed at harnessing intriguing photophysical characteristics from π‒aromatic group substituted o -carborane compounds. We investigate the optical properties of two compounds, one with H- (ICH) and the other with trimethylsilyl- (ICSi) substituted o -carborane, both linked to indolo[3,2,1- jk ]carbazole. This compound exhibits a planar geometry and an electron-abundant nature. Interestingly, in their crystalized solid states, both compounds exhibit multiple luminescent properties that can be divided into three emissive parts: locally excited (LE), crystallization-induced excimer (EX), and intramolecular-charge-transfer (ICT) states. However, in solution, the PL spectra reveal only the LE-based emissive band only in the high-energy region (λ em ≈ 380 nm). Analysis of the crystal structures of these compounds reveals notable geometric difference, providing crucial insights to elucidate the origin of each emissive pattern. The well-overlapped π‒π interaction between ICH dimer molecules and the perfect orthogonal geometry around the o -carborane of ICSi molecule explain why the EX- and ICT-based emissions dominate the PL spectra of ICH and ICSi crystals, respectively. In particular, ICH crystals exhibited an intriguing feature: white emission (Commission internationale de l'éclairage 1931 coordinates = 0.29, 0.30), resulting from the collaboration of a multi-luminescent pattern within a single-molecule packing system. Furthermore, the reduced rate constants (k IET) for intramolecular energy transfer (IET) from LE-to EX- and ICT-based emission strongly indicate the occurrence of a cascade IET phenomenon in the crystalline packing system. These findings validate that specific molecular design and functional substitutions around the o -carborane of π‒conjugated carboranyl luminophores play an essential role in inducing intriguing photophysical characteristics. [Display omitted] • Preparation of H- (ICH) and trimethylsilyl- (ICSi) substituted o -carborane, both linked to indolo[3,2,1- jk ]carbazole. • Both compounds exhibit multiple luminescent properties in their crystalized states. • ICH crystals exhibited a white emission resulting from the multi-luminescent pattern. • Insight for specific functional substitution to induce intriguing emissive characteristics. [ABSTRACT FROM AUTHOR]

We herein report the preparation of two compounds (C1 and C2) with an ortho‐carborane cage appended at the C4‐position of the fluorene (C1) or carbazole (C2) moiety of their spiro[fluorene–carbazole] scaffolds. Photoluminescence spectra of both compounds in solution at 298 K did not demonstrate any emissive trace; however, those of both compounds in solution at 77 K and in the film state exhibited strong orange emission. Interestingly, the quantum efficiency and radiative decay constant of C2 in the film state were much higher than that of C1. This distinctly showed that the position of the o‐carborane unit on the scaffold strongly affected the efficiency of the radiative decay process based on intramolecular charge transfer (ICT) transitions. These findings revealed that that the electronic environment of the scaffold‐molecule linked with the o‐carborane cage plays an important role to control the ICT‐based radiative decay process. [ABSTRACT FROM AUTHOR]

The bulk polymerization behavior of l-lactide monomer using dibenzoylmethane ( DBM)-based Sn( II) compounds ( DBM)Sn( OBu) ( 2) and ( DBM) 2Sn ( 3) is investigated. Compounds 2 and 3 were prepared from the reaction of Sn( OBu)2 ( 1) with 1 or 2 equiv of DBM, respectively. X-ray diffraction studies revealed that, while 2 exists as a dimeric form linked by 1-butoxide bridges, 3 is monomeric in the solid state. The Sn( II) centers in both compounds adopt distorted square-pyramidal geometry. Ring-opening polymerization of l-lactide with 1-3 efficiently produced poly( l-lactide)s with high molecular weight and narrow polydispersities ( PDI < 2). The catalytic activity was found to be in the order 1 > 2 > 3, indicating that the DBM ligand causes a sluggish coordinative insertion of the lactide monomer into the Sn( II) center. In particular, the addition of dodecanol ( DDO, 0.1 mol%) substantially improved the catalytic activity for all compounds. The comparative polymerization using Sn(Oct)2 (Oct = 2-ethylhexanoate) in the absence and presence of DDO further showed that 1 is higher in activity than Sn(Oct)2 and that Sn( II) alkoxides are the actual active species in the polymerization of l-lactide. [ABSTRACT FROM AUTHOR]

Naphthyl‐ and quinoline‐appended o‐carboranyl compounds, NCB and QCB, respectively, were prepared and characterized by multinuclear nuclear magnetic resonance spectroscopy, elemental analysis, and single crystal X‐ray diffraction. Although both the compounds were non‐emissive in the solution state at 298 K, they were photoluminescent in the rigid state (in THF at 77 K and film state) in the region 450–550 nm. Theoretical calculation of the optimized structure in the S1 state suggested that the low‐energy emissive bands for NCB and QCB were attributed to intramolecular charge transfer (ICT) transition. Intriguingly, the C−C bond axis of the o‐carborane in NCB in the solid state was more orthogonal to the plane of the appended aromatic group than that in QCB, indicating relatively high delocalization between the o‐carborane and aromatic moieties of NCB. The quantum efficiency and radiative decay constant of the ICT‐based emission of NCB in the film state were much higher than those of QCB. These findings imply that the structural geometry around the C−C bond axis of the o‐carborane is a decisive factor in accelerating the ICT‐based radiative decay in the o‐carbonyl luminophores in the rigid state. [ABSTRACT FROM AUTHOR]

Heteroleptic (CN)2Ir(acac) (CN = 4-CBppy (I); 5-CBppy (2), 4-fppy (4) CB = ortho-methylcarborane; ppy = 2-phenyIpyridinato-Cz,N, 4-fppy = 2-(4-fluorophenyl )-pyridinato-C²,N, acac = acetylacetonate) complexes were prepared and characterized. While 1 exhibits a phosphor-escence band centered at 531 nm, which is red-shifted compared to that of unsubstituted (ppy)2Ir(acac) (3) (λem = 516 nm), the emission spectrum of 2 shows a blue-shifted band at 503 nm. Comparison with the emission band for the 4-fluoro-substituted 4 (λem = 493 nm) indicates a substantial bathochromic shift in 1. Electrochemical and theoretical studies suggest that while carborane substitution on the 4-position of the phenyl ring lowers the ³MLCT energy by a large contribution to lowest unoccupied molecular orbital (LUMO) derealization, which in turn assigns the lowest triplet state of 1 as [dπ(ir)--π*(CAT)]³MLCT in character, the substitution on the 5-position raises the ³MLCT energy by the effective stabilization of the highest occupied molecular orbital (HOMO) level because of die strong inductive effect of carborane. An electroluminescent device incorporating 1 as an emitter displayed overall good performance in terms of external quantum efficiency (6.6%) and power efficiency (10.7 lm/W) with green phosphorescence. [ABSTRACT FROM AUTHOR]

Abstract: Triarylborane–phenanthroimidazole conjugates 1 and 2 linked by a biphenylene and phenylene group, respectively, were prepared and characterized. Both compounds are highly fluorescent (Φ =0.49–0.74 for 1 and Φ =0.71–0.92 for 2) and show a positive solvatochromism. Upon fluoride binding to the boron center, they exhibit a ratiometric fluorescence response (Δλ em =84nm for 1 and 63nm for 2 in acetone) accompanying a vivid emission color change. Photophysical data and TD-DFT studies suggest that intramolecular charge transfer (ICT) transition from a phenanthroimidazole donor to a borane acceptor in the neutral 1 is switched to π–π* transition of phenanthroimidazole moiety after fluoride binding. Due to the greater elevation of LUMO level by fluoride complexation, the resulting fluoride adduct [1F]− fluoresces at the apparently blue-shifted region. [Copyright &y& Elsevier]

Abstract: A well-dispersed multiwall carbon nanotube (MWCNT)/syndiotactic polystyrene (sPS) composite was prepared by simple in-situ polymerization of styrene using pentamethylcyclopentadienyltitanium(IV) trimethoxide (Cp*Ti(OMe)3) attached to the shortened and functionalized MWCNT (f-MWCNT). The attachment of Cp*Ti(OMe)3 to the f-MWCNT was confirmed by thermogravimetric analysis, X-ray photoelectron spectroscopy, Fourier transformed infrared spectroscopy, and energy dispersive X-ray spectroscopy. Cp*Ti(OMe)3 attached to pristine MWCNT in the presence of methylaluminoxane (MAO) did not produce PS, whereas Cp*Ti(OMe)3 attached to f-MWCNT showed a high catalytic activity for the syndiospecific polymerization of styrene under the same polymerization conditions. Obtained sPS showed a narrow molecular weight distribution (PDI ≈ 2), a high SI value (≥90%), and a high melting point (≈272 °C). Scanning electron microscopy and transmission electron microscopy images showed that MWCNT strands were well dispersed in the MWCNT/sPS composite. Such composites had greatly improved thermal stability compared to normal sPS polymers. [Copyright &y& Elsevier]

Abstract: Three monomeric germatranes, 1-isopropoxy-3,3,7,7,10,10-hexamethyl-2,8,9-trioxa-5-aza-1-germatricyclo[3.3.3.01,5]undecane (1), 1-isopropoxy-3,3,7,7-tetramethyl-2,8,9-trioxa-5-aza-1-germatricyclo[3.3.3.01,5]undecane (2), and 1-isopropoxy-3,3-dimethyl-2,8,9-trioxa-5-aza-1-germatricyclo[3.3.3.01,5]undecane (3) have been synthesized by the reaction of Ge(O-i-Pr)4 in refluxing toluene with corresponding triethanolamines, (HOCH2CH2) n N(CH2CMe2OH)3− n (n =0, L1H3 ; n =1, L2H3 ; n =2, L3H3 ), where the number of CMe2 groups adjacent to a OH functionality varied from 3 (L1H3 ) to 2 (L2H3 ), and to 1 (L3H3 ). These germatranes 1–3 have been characterized by solution 1H and 13C{1H} NMR and the solid state structure of 2 has been determined by single crystal X-ray diffraction. [Copyright &y& Elsevier]

The development of highly efficient and long‐life deep blue devices has been an ongoing challenge in the field of organic light‐emitting diodes (OLEDs) because of the short lifetime inherent to highly efficient blue devices. The efficiency and lifetime issues of the deep blue OLEDs are resolved in this work by engineering the device architecture by managing the triplet excitons of the phosphorescence and thermally activated delayed fluorescence (TADF) emitters. The CN‐modified imidazole type Ir emitter and boron‐based TADF emitter with similar emission energy are combined to develop an energy exchanging phosphorescence and TADF (EPHTADF) device. An emission mechanism inducing both forward and backward energy transfer concurrently between the Ir phosphor and TADF emitter shortens the triplet exciton lifetime of the two emitters, which dramatically enhances the device lifetime of the blue devices. Deep blue OLEDs triggering EPHTADF emission ultimately yields device performances including high current efficiency (CE) of 37.0 cd A−1, color‐coordinate corrected CE of 430.9 cd A−1, extrapolated device lifetime of more than 30 000 h, and deep blue color coordinates of (0.122, 0.086). This work demonstrates the potential of EPHTADF devices to serve as the solution to the problematic issues of the blue OLEDs. [ABSTRACT FROM AUTHOR]

Although studies have investigated various N‐heterocyclic‐based Ir(III)‐cyclometalates that exhibit high efficiency and electrochemical stability, blue‐phosphorescent Ir(III) complexes with further improved efficiency and blue‐emission purity are needed for use as emitters in organic light‐emitting diodes (OLEDs). Therefore, the preparation and comprehensive characterization of a phenyl‐1,2,4‐triazole‐based facial‐homoleptic iridium(III) complex, TzIr (fac‐tris(1‐(2,6‐diisopropylphenyl)‐3‐methyl‐5‐phenyl‐1H‐1,2,4 triazolyl)iridium(III)) is herein described. The complex shows a definite blue‐emission band (λem = 456 nm) in the solution and film states at ambient temperature. Moreover, this complex exhibits considerably high phosphorescent quantum efficiency (80%) and thermal stability (Td5 = 362 °C). Multilayer phosphorescent OLEDs using TzIr as the emitter and 3,3‐di(9H‐carbazol‐9‐yl)biphenyl (mCBP)/ 9‐(3′‐(9H‐carbazol‐9‐yl)‐5‐cyano‐[1,1′‐biphenyl]‐3‐yl)‐9H‐carbazole‐3‐carbonitrile (CNmCBPCN) as the mixed host are fabricated. The devices exhibit outstanding performance, with a high external quantum efficiency (27.8%), current efficiency (38.7 cd A−1), and CIEy (y coordinate value of the Commission Internationale de l'Eclairage color space) less than 0.18. The results of this study indicate that this novel 1,2,4‐triazole‐based dopant, TzIr, is a promising candidate for developing highly efficient blue‐phosphorescent emitters for use in OLEDs. [ABSTRACT FROM AUTHOR]

5-Phenyl-1,2,4-triazole-appended closo- (CB1 and CB2) and nido-o-carboranyl (nido-CB1 and nido-CB2) compounds were prepared and fully characterized using multinuclear NMR spectroscopy and elemental analysis. The solid-state molecular structures of both closo-compounds were analyzed by X-ray crystallography. Although the closo-compounds exhibited dual emissive patterns in the rigid state (in THF at 77 K), which were assignable to a π–π* local excitation (LE)-based emission (λem = ca. 380 nm) on the triazole moieties and to an intramolecular charge transfer (ICT)-based emission (ca. 460 nm) in which the o-carborane units acted as the acceptor (A), at 298 K in THF, the LE-based emission dominated. In contrast, the nido-compounds exhibited an intensive emission originating from ICT transitions in which the o-carborane units reversibly acted as the donor (D). In particular, the positive solvatochromic effects of both nido-compounds and the results of theoretical calculations for the o-carboranyl compounds supported the electronic role of the o-carboranyl unit in each compound. Investigation of the radiative decay mechanism of the closo- and nido-compounds using their quantum efficiency (Φem) and decay lifetime (τobs) suggested that the ICT-based radiative decay of nido-compounds occurred more efficiently than the LE-based decay of closo-compounds. These results implied that emission from the closo-compounds was drastically enhanced by the deboronation reaction upon exposure to an increasing concentration of fluoride anions, and finally became similar to the emission color (sky-blue) of the nido-compounds. [ABSTRACT FROM AUTHOR]

The introduction of an o-carborane cage into the triarylborane significantly enhances the Lewis acidity of the boron atom leading to large increase in fluoride ion affinity. [ABSTRACT FROM AUTHOR]

Herein, to elucidate the effect of substituent electronic properties on the photophysical properties of indium‐based organometallic luminophores, we prepare a series of indium complexes (1–5) with salen ligands bridged by an electron‐withdrawing 4,5‐dichlorophenylene (Cl2Ph) unit. The structures of all the complexes are fully confirmed by 1H and 13C NMR spectroscopy as well as elemental analysis. In particular, the molecular structure of 3, confirmed by X‐ray crystallography, is monomeric and the central indium atom adopts a square‐pyramidal geometry. The UV/Vis and fluorescence spectra of 1–5 show typically salen‐centered intramolecular charge transfer transitions with gradual bathochromic shifts as the electron‐donating ability of the substituents increases. This feature is further supported by electrochimical studies. Furthermore, the lowest unoccupied molecular orbital energy levels of 1–5 are considerably lower (approximately −3.70 eV) than those of salen‐based indium complexes with other aryl‐bridging units owing to the reduced electron‐donating effect of the (Cl2Ph)salen group. [ABSTRACT FROM AUTHOR]

We herein reported the preparation of three heteroleptic iridium complexes possessing the monodentate benzo[d]imidazole ligand, namely IrBzH (bis[2‐(4,6‐difluorophenyl)pyridinato‐C^N](1‐pyridin‐2‐yl)‐1H‐benzo[d]imidazolate)iridium(III)), IrBzCN (bis[2‐(4,6‐difluorophenyl)pyridinato‐C^N](2‐(1H‐benzo[d]imidazolate‐1‐yl)isonicotinonitrile)iridium(III)), and IrBzBr (bis[2‐(4,6‐difluorophenyl)pyridinato‐C′N](1‐(4‐bromopyridin‐2‐yl)‐1H‐benzo[d]imidazolate)iridium(III)). The successful preparation of these complexes was confirmed by multinuclear NMR spectroscopy and elemental analysis, while the molecular structures were determined by X‐ray diffraction. The photoluminescence spectra of all three complexes in toluene at ambient temperature exhibited a dual‐emissive pattern in the high‐ and low‐energy regions. For IrBzCN and IrBzBr, the emissions were simultaneous in accordance with the excitation energies (λem = 342 and 370 nm), indicating that exhibiting both fluorescent (in the high‐energy region) and phosphorescent (in the low‐energy region) emissions is an inherent property of these complexes. Time‐dependent density functional theory calculations verified that each fluorescent emission of the Ir complexes is associated with a ligand‐to‐ligand charge transfer transition, and the phosphorescent emission can be attributed to typical triplet metal‐to‐ligand charge transfer transitions between Ir3+ and the difluorophenylpyridine ligand. [ABSTRACT FROM AUTHOR]

9,9′‐Spirobifluorene‐based closo‐o‐carboranyl (SFC1 and SFC2) compounds and their nido‐derivatives (nido‐SFC1 and nido‐SFC2) were prepared and characterized. The two closo‐compounds displayed major absorption bands assignable to π–π* transitions involving the spirobifluorene group, as well as weak intramolecular charge‐transfer (ICT) transitions between the o‐carboranes and their spirobifluorene moieties. The nido‐compounds exhibited slightly blueshifted absorption bands resulting from the absence of the ICT transitions corresponding to the o‐carborane moieties due to the anionic character of the nido‐o‐carboranes. While SFC1 exhibited only high‐energy emissions in THF at 298 K (only from locally excited (LE) states assignable to π–π* transitions on the spirobifluorene group), remarkable emissions in the low‐energy region were observed in the rigid state such as in THF at 77 K and in the film state. SFC2 displayed intense emissions in the low‐energy region in all states. The fact that neither of the nido‐derivatives of SFC1 and SFC2 exhibited low‐energy emissions and the TD‐DFT calculation results of each closo‐compound clearly verified that the low‐energy emission was based on ICT‐based radiative decay. The conformational barriers from each relative energy calculation upon changing the dihedral angles around the o‐carborane cages for both compounds confirmed that the rotation of the o‐carborane cages and terminal phenyl rings for SFC1 is freer than that for SFC2. [ABSTRACT FROM AUTHOR]

To clarify the relationship between planarity and intramolecular charge transfer (ICT), two o-carboranyl compounds (TCB and FCB) containing different ortho-type terphenyl rings, namely, perfectly distorted or planar phenyl rings, were synthesised and fully characterised. Although the emission spectra of both compounds presented intriguing dual-emission patterns in solution at 298 or 77 K and in the film state, distorted TCB mostly showed locally excited emission, whereas planar FCB demonstrated intense emission corresponding to an ICT transition. Interestingly, the emission efficiencies and radiative decay constants of terphenyl-based o-carboranyl compounds were gradually enhanced by increasing the planarity of the terphenyl groups. These results verify the existence of a strong relationship between the planarity of appended aryl groups and ICT-based radiative decay in o-carborane-substituted compounds. [ABSTRACT FROM AUTHOR]

The carborane (CB)-functionalized ligand was installed in a variety of MOFs through postsynthetic ligand exchange processes. This methodology is a general method for preparing o-CB-functionalized MOFs with known frameworks. Furthermore, the photoluminescence (PL) spectra revealed intriguing aggregation-induced emission (AIE) features following the systematic incorporation of o-CB functionalities into framework-type materials. [ABSTRACT FROM AUTHOR]

Organic light-emitting diodes (OLEDs) play a key role in modern flexible displays. Although stable and efficient red- and green-emitting phosphors have been developed, the applications of blue emitters are limited due to their poor chemical and electrochemical stability, and thus, they require further development. Herein, we report the preparation and full characterization of IrTrz , a 3-methyl-5-phenyl-1 H -1,2,4-triazole-ligand-based facial -homoleptic iridium complex. Single-crystal X-ray diffractometry results suggested that the complex is a facial isomer with C 3 point symmetry. The complex exhibited a blue emission band centered at ∼450 nm in both solution and the film state at ambient temperature; moreover, it showed a very narrow full-width at half maximum value (55 nm) and a moderate photoluminescence quantum yield (33%). The complex showed high thermal stability, with 5%-weight-loss and glass-transition temperatures of 324 and 210 °C, respectively. Consecutive cyclic voltammetry measurements revealed outstanding electrochemical stability of the complex. Therefore, multilayer phosphorescent OLEDs that use IrTrz as the blue emitter were fabricated with two types of host material: (3,3′-di(9 H -carbazol-9-yl)-1,1′-biphenyl (mCBP) and 9-(dibenzo[ b,d ]thiophen-4-yl)-9 H -3,9′-bicarbazole (4DBTCz)). In particular, the 4DBTCz-based devices exhibited low turn-on voltages (∼5.0 V) and high external quantum efficiencies (>11%) with a Commission Internationale de l'Eclairage y -coordinate of 0.2. Moreover, the devices demonstrated stable operational lifetimes that exceeded 690 h (for mCBP) and 390 h (for 4DBTCz) at 100 cd/m2. Therefore, we believe that the 1,2,4-triazole-ligand-based Ir(III) complex is a promising blue-phosphorescent emitter material for applications in stable and efficient OLED devices. [Display omitted] • We report a novel Ir(III) complex with outstanding photophysical properties suitable for blue phosphorescence. • OLED devices doped with the complex exhibited distinct blue emissions, low turn-on voltages, and high efficiencies. • The phosphor is highly thermally and electrochemically stable, leading to devices with long operating lifetimes over 690 h. • Insight for strategic molecular-design of blue phosphorescent emitter showing high efficiency and stability. [ABSTRACT FROM AUTHOR]

This study investigates the photophysical features of aromatic conjugated o -carboranes and provides strong evidence for the relationship between their molecular geometry and photoluminescence efficiency. Four 2-phenylnaphthalene appended o -carboranyl luminophores, each with a different 2-phenyl ring distortion angle (1F , 2P , 3M , and 4I) were prepared and characterized. In particular, the geometric features around the 2-phenyl ring in the crystalline state were fully determined using single-crystal X-ray diffraction. All compounds in rigid states (solution at 77 K and solid states) demonstrated strong intramolecular charge-transfer (ICT)-based emissions in the yellowish-green region. Intriguingly, the quantum efficiency of the ICT-based emission gradually decreased as the distortion of the terminal 2-phenyl ring increased. Furthermore, the radiative decay constant of 1F was five times that of 4I , whereas the nonradiative decay of 1F was less than one-third that of 4I. In addition, theoretical modeling of the low-energy transition in the first excited state of 2P upon the rotation of the 2-phenyl ring revealed that the distorted geometry strongly affects the ICT-based radiative process. This model strongly suggests that the ICT-based radiative efficiency of π‒conjugated o -carborane is significantly affected by the geometry of the appended aromatic group. [Display omitted] • Preparation of four 2-phenylnaphthalene appended o -carboranyl luminophores, each with a different 2-phenyl ring distortion. • Intramolecular-charge-transfer based radiative efficiency distinctly depending on the 2-phenyl ring distortion angle. • Insight for molecular design of π‒aromatic conjugated o -carboranyl luminophores to induce high radiative efficiency. [ABSTRACT FROM AUTHOR]

Europium is a lanthanide rare‐earth metal and is known as a key element in luminophore development. Since europium has two relatively stable oxidation states, Eu2+ and Eu3+, which is exceptional among the various lanthanide elements, we have developed a europium‐catalyzed aerobic oxidation with external oxidants utilizing the redox cycle of Eu2+/Eu3+. The reaction was performed under mild conditions with a wide substrate scope. The photoluminescence spectra clearly demonstrate the oxidation state changes that occur during the presented europium‐catalyzed aerobic oxidation. [ABSTRACT FROM AUTHOR]

2-Phenylpyridine- and 2-(benzo[b]thiophen-2-yl)pyridine-based (ppy- and btp-based) o-carboranyl (Car1 and Car2) and their B(CH3)2-C∧N-chelated (Car1B and Car2B) compounds were prepared and fully characterised by multinuclear NMR spectroscopy and elemental analysis. The solid-state structure of Car2B was determined by single-crystal X-ray diffraction, which revealed a four-coordinated dimethylboryl centre. All compounds displayed major absorption bands that were assigned to π–π* transitions involving the ppy and btp moieties, as well as weak intramolecular charge-transfer (ICT) transitions between the o-carboranes and their aryl groups. Furthermore, the chelated compounds exhibited dominant low-energy absorption bands (λabs = 333 nm for Car1B and 383 nm for Car2B) resulting from the reinforcement of ICT transitions that correspond to the o-carborane moieties through the restriction of aromatic-ring free rotation. While Car1 and Car2 did not exhibit photoluminescence emissions in toluene at 298 K, Car1B and Car2B showed intense emissions, which are assignable to π–π* transitions associated with each chelated aryl group. However, Car1 and Car2 evidently emitted at around 450 nm in solution at 77 K, invoked by radiative ICT transitions between the carborane and the ppy or btp moiety, indicating that ICT-based radiative decay is only invigorated in the rigid state in the absence of structural variations, such as C–C bond fluctuations in the carborane cage and aromatic-ring free rotation. Interestingly, while Car1 in the film state exhibited a weak ICT-based emission spectrum, and Car1B and Car2B showed intense emissions originating from π–π* transitions associated with each chelated aryl group, Car2 showed significantly enhanced emissions in the same energy region as that exhibited in solution at 77 K, resulting in a much larger quantum efficiency over that in solution. DFT-optimised structures of Car1 and Car2 in their ground and the first-excited states clearly reveal that the enhanced emissive features of Car2 in the film state are strongly associated with the retained planarity of the btp moiety in both the ground and excited states. The photophysical results for these o-carboranyl compounds definitively reveal that the planarities of the aryl groups appended to the o-carborane decisively affect the efficiency of radiative decay based on ICT involving the o-carborane. [ABSTRACT FROM AUTHOR]

A series of indium complexes with salen ligands bridged by aryl groups such as [Ar-{N CH(C 6 H 2 -3- t Bu-5-R)} 2 ]In-Me (Ar = 4,5-dimethyl-1,2-phenylene, 1,2-phenylene, and 3,4-naphthylene; R = H, Br, t Bu, Me, OMe, NMe 2 , and NMe 3 + ) were prepared and fully identified by NMR spectroscopy and elemental analysis. All indium complexes are highly stable in air and aqueous solutions. Among these complexes, the structurally characterized complexes [(4,5-dimethylphenylene)bis(3- tert -butyl-5-methylsalicylideneiminato)-κ N , N′ , O , O' ]methylindium(III) and [(2,3-naphthanlene)bis(3- tert -butyl-5-methylsalicylideneiminato)-κ N , N′ , O , O' ]methylindium(III) have slightly distorted square-pyramidal geometries around the central indium atoms. The UV/Vis absorption and emission spectra of all indium complexes exhibited significant intramolecular charge transfer (ICT) transitions assigned to the aryl salen-centered π-π* transitions, which displayed a gradual bathochromic shift, resulting from the electronic alteration of the substituent at the C5 position of phenoxy ring. Furthermore, the emission bands also gradually red-shifted as the electron-donating effect of bridging aryl groups decreased. In particular, the emission spectra of the indium complexes were observed in the visible region ranging from green (ca. 500 nm) to deep red (ca. 700 nm). The colors were obtained by manipulating the HOMO and LUMO energy levels, which was further supported by both electrochemical data and theoretical calculations. [ABSTRACT FROM AUTHOR]

In this study, we synthesized quinolinol‐ligand (2‐methylquinolin‐8‐ol, q)‐based aluminum complexes with phenyl (D1), biphenyl (D2), and naphthyl (D3)‐bridged triarylboranes, and employed them as organometallic chemosensors for sensing mediated by fluoride anions. In addition, these dyad complexes were fully characterized by multinuclear nuclear magnetic resonance (NMR) spectroscopy and elemental analysis. UV/Vis titration experiments examining the association of D1, D2, and D3 with fluoride demonstrated that the dyad complexes associated in a 1:1 binding stoichiometry in tetrahydrofuran (THF), with binding constants (K) in the range of 2.7–6.6 × 104 M−1. Moreover, these dyad complexes showed a ratiometrically decreasing fluorescence response in photoluminescence titration experiments upon binding of fluoride to the borane moiety, thereby giving rise to a turn‐off chemosensor for detection of fluoride anions. It could be postulated that these turn‐off properties were caused by the interruption of the intramolecular charge‐transfer (ICT) transition between the q2Al part and the bridged phenoxy groups. Furthermore, the theoretical calculation results for the dyad complexes and these fluoride adducts clearly indicate that the ICT transition between the q2Al and bridged phenoxy groups of the complexes could be interrupted by the binding of fluoride to borane. [ABSTRACT FROM AUTHOR]

A novel class of salen–Al/carbazole dyads (D1 and D2) was synthesized and fully identified. The emission spectra of the dyads presented intriguing dual-emission patterns via an intramolecular energy transfer (IET) state in solution. Furthermore, the IET feature of the dyads was clearly observed in the rigid state. Interestingly, the emission efficiency of the dyads was enhanced by the significant IET process from the carbazole group to the salen–Al moiety. Particularly, D1 exhibited a nearly three-fold enhanced luminescence efficiency compared to the corresponding mononuclear aluminum complexes (A1). Such an emission process of these guest–host systems was further supported by theoretical calculation. [ABSTRACT FROM AUTHOR]

Salen-based indium triads, [{(3-tBu)2-(5-Mes2B)2-salen}In-Me] (1) and [{(3-tBu)2-(5-Mes2Bphenyl)2-salen}In-Me] (2), bearing triarylborane (TAB) units were prepared and fully characterised by NMR spectroscopy and elemental analysis. The major absorption bands of 1 and 2 appeared in the region centred at 347 nm and 374 nm, respectively, and the intense emission spectra were observed in the sky blue (λem = 491 nm for 1) and bluish-green (λem = 498 nm for 2) regions, respectively. The solvatochromism effects in various organic solvents and computational calculation results strongly suggested that these absorption and emission features are mainly attributed to intramolecular charge transfer (ICT) transitions between the salen ligand moieties and the TAB units. Furthermore, UV-vis and photoluminescence (PL) titration experiments by the addition of fluoride anions demonstrated ratiometric quenching patterns in both the absorption and emission spectra, indicating that binding of the fluoride anion to the boron centres interrupts these ICT transitions in each compound. Interestingly, both triads exhibited a gradual red-shifted response in each emission spectrum upon the addition of the fluoride anions, resulting in a dramatic colour-change to yellow. The computational calculation results of the S1 states revealed that these emission-colour change properties arise from the elevation of HOMO levels, which are mainly localised on the TAB moieties, resulting from the fluoride anion binding to the borane centres. [ABSTRACT FROM AUTHOR]

Abstract: A new concept of host, electroplex host, is developed for high efficiency and long lifetime phosphorescent organic light‐emitting diodes by mixing two host materials generating an electroplex under an electric field. A carbazole‐type host and a triazine‐type host are selected as the host materials to form the electroplex host. The electroplex host is found to induce light emission through an energy transfer process rather than charge trapping, and universally improves the lifetime of red, yellow, green, and blue phosphorescent organic light‐emitting diodes by more than four times. Furthermore, the electroplex host shows much longer lifetime than a common exciplex host. This is the first demonstration of using the electroplex as the host of high efficiency and long lifetime phosphorescent organic light‐emitting diodes. [ABSTRACT FROM AUTHOR]

The reaction of three equivalents of 5-(2,4-dihydroxyphenyl)-1 H -tetrazole (H 3 dhptz ) with iron(III) perchlorate in the presence of potassium hydroxide afforded the metallascorpionate framework. By simple recrystallization, an interesting coordination polymer, [K 4.5 Fe( dhptz ) 1.5 (H dhptz ) 1.5 DMF 7 (H 2 O) 3.5 ] n , was obtained. It possesses two potassium ions with either κ 3 - O or κ 3 - N binding modes, resulting in an array of K–Fe–K metal ions and a short Fe–K distance (3.427 Å). One scorpionate ligand possesses 4.5 potassium ions at six different positions in the solid state by means of the bridging oxygen atoms of the DMF solvent. Further coordination modes between the potassium ions and water/DMF provide a one-dimensional (1-D) metallascorpionate array and allow the formation of a 3-D hexagonal coordination network. [ABSTRACT FROM AUTHOR]

1,3,5-Tris-( o- carboranyl-methyl)benzene ( closo - 1) and its nido -form ( nido - 1 ) were synthesized and fully characterized. The solid-state molecular structure of closo - 1 was determined by single-crystal X-ray diffraction analysis. Compound closo - 1 exhibited an intense single emission in various organic solvents that was red-shifted with increasing solvent polarity. The positive solvatochromic effect and theoretical calculation results at the first excited (S 1 ) optimized structure of closo - 1 strongly suggest that this emissive band can be assigned to an intramolecular charge transfer. Meanwhile, nido - 1 showed a pronounced red-shift of the emissive band compared to that of closo - 1 and aroused low-energy emission. The specific emissive features of nido - 1 were attributed to the elevation of its HOMO level, estimated by cyclic voltammetry. The photophysical changes by conversion from closo - 1 to nido - 1 allowed the emissive color-tunable sensing of fluoride. Thus, the tris- o -carboranyl compound showed great potential as a chemodosimeter for fluoride anion sensing, detectable by the naked-eye. [ABSTRACT FROM AUTHOR]

Fluorescent molecules have been used for various applications in biological system monitoring. Considering the complexity of cellular systems, there is a huge demand for diverse fluorescent organic molecular scaffolds. However, only a limited number of fluorescent scaffolds have been reported due to the lack of a rational design strategy. We serendipitously discovered N4-phenylquinazoline-4,6-diamine as a fluorescent scaffold with turn-on characteristics. To improve the photophysical property of the initial fluorescence molecule, we synthesized derivatives of the N4-phenylquinazoline-4,6-diamine and found systematic correlation between electronic density of the phenyl substituent of the scaffold and fluorescence intensity. Through tuning the photophysical property of the scaffold and a rational design strategy, we developed N4-dichlorophenylquinazoline-4,6-diamine as a potential fluorophore for various biological applications. To prove the value of the developed fluorescent scaffold, we devised formaldehyde (FA) fluorescent sensor by tailoring amine on 6-position of N4-dichlorophenylquinazoline-4,6-diamine to employ a 2-aza-Cope rearrangement as the molecular detection mechanism with double-digit nanomolar detection limits. FA level in live HeLa cells were successfully visualized with the probe, exhibiting that N4-dichlorophenylquinazoline-4,6-diamine can serve as a useful molecular scaffold for offering various fluorescent sensors toward the investigation of physiological and pathological processes in live cells. [Display omitted] • A new tunable fluorescent molecular scaffold, N4-phenylquinazoline, was discovered. • A structure photophysical property relationship of the scaffold was unveiled. • The relationship has led to the rational design of a formaldehyde sensor, QFP. • Reaction between formaldehyde and QFP trigger aza-Cope rearrangement. • Rearrangement reaction of QFP allowed sensing of formaldehyde in live cell. [ABSTRACT FROM AUTHOR]

Multiple o-carborane substituted compounds, mono-, 1,3-bis-, and 1,3,5-tris[2-(4-butylphenyl)-o-carboran-1-yl]benzene (1-3), were prepared and characterized by multi- nuclear NMR spectroscopy and elemental analysis. The solid- state structures of 2 and 3 were also confirmed by single-crystal X-ray diffraction. While the mono-carborane compound 1 was nonemissive in the solution state at 298 K, the photoluminescence (PL) spectra of 2 and 3 exhibited weak-to-moderate emission (λem = 352 nm for 2 and 363 nm for 3 in THF). Compounds 2 and 3 showed intriguing dual emission bands (λem = 361 and 537 nm for 2 and λem = 387 and 520 nm for 3) at 77 K, and in film, of which the low-energy band was dominant in the solid state. TD-DFT calculations on the S1 optimized structures suggested that the low-energy fluorescence of 2 and 3 was attributed to the π(4-butylphenyl) → π*(phenylene-o-carborane) intramolecular charge-transfer transition. The low-energy electronic transition of 2 and 3 was apparently associated with aggregation-induced emission, and an enhanced emission intensity (λem = ca. 570 nm for 2 and λem = ca. 550 nm for 3) was observed upon increasing the water fraction (fw) in THF/water mixtures. Furthermore, the PL spectroscopic experiments of poly(3-hexylthiophene-2,5-diyl) (P3HT) polymer films doped with 3 revealed the excellent electron-accepting properties of 3. [ABSTRACT FROM AUTHOR]

From an industrial/engineering point of view, the greatest demerit of solely isosorbide (ISB)-based polycarbonate is its fragility; this is considerably overcome in this study by using a dual-diol strategy with 1,4-cyclohexanedimethanol (CHDM). A series of copolycarbonates of ISB, a bio-derived diol with a rigid heterocyclic structure, and ductile CHDM monomers with diphenyl carbonate were prepared by transesterification polymerization. The weight-average molecular weight of the polycarbonates gradually decreases as the ratio of ISB increases; however, their T g and storage modulus increase. The ultimate elongation of the copolycarbonates is enhanced from 4.6 to 20% as the content of CHDM is increased from 30 to 80 mol%. ISB content greater than 50 mol% makes the copolycarbonates strong but brittle, and ISB content less than 50 mol% makes the copolycarbonates ductile but soft. The polycarbonate with 70/30 mol% of ISB/CHDM shows a 1.25-fold higher Young's modulus, 1.05-fold higher ultimate tensile strength, and one-grade higher pencil hardness than the bisphenol-A (BPA)-based polycarbonate. Interestingly, the hydrophilic ISB content does not affect the degree of hydrophilicity of the copolycarbonate samples. Water droplet contact angles are in the range of 81–87°, comparable to that of the BPA-based polycarbonate. [ABSTRACT FROM AUTHOR]

We developed a novel π-extended diazatriphenylene derived highly fluorescent Ru-complex as a photo-induced anti-cancer agent by generating radical species inside the cells. [Display omitted] • We developed Ru(II)-complex of the π-extended, novel diazatriphenylene. • The Ru(II)-complex is highly luminescent with excellent quantum yield of ∼0.8. • The Ru(II)-complex showed photo-induced cytotoxicity with a submicromolar IC 50. • Photo-activated Ru(II)-complex generates radical species resulting cellular damage. Novel bipyridine-based heterocyclic building block, 3,10-dichloro-benzo[f][1,10]phenanthroline and its Ruthenium(II) complex have been synthesized and fully characterized. The synthesized Ru(II)-complex is highly luminescent displaying emission at 590 nm with quantum yield of ∼0.8 in methanol. Ru(II) complex showed photocytotoxicity upon 400 nm blue light irradiation. Mechanistic study revealed that photoactivated Ru(II) complex generates reactive radical species which can damage the protein inside the cells and induce cell death even with short irradiation time. [ABSTRACT FROM AUTHOR]

Three novel carboline-based benzothiadiazole compounds, αCB , βCB , and γCB , bearing α-, β-, and γ-carboline, respectively, were synthesized and characterized. The molecular structures of αCB and γCB in the crystalline state were analyzed using single-crystal X-ray diffraction. The UV–vis absorption and photoluminescence spectra of all compounds displayed typical intramolecular charge transfer (ICT) characteristics, resulting in clear solvatochromic effects in various organic solvents. Theoretical calculations also verified that the major electronic transitions of the three compounds could be assigned to the ICT transition between the carboline moiety (as the electronic donor, D) and benzothiadiazole center (as the acceptor, A). The unit cell of the crystal structure of αCB revealed two solvent (chloroform) molecules residing in the space between the two α-carboline moieties via hydrogen bonding, which could inhibit the structural fluctuation of this compound. Given this feature, αCB demonstrated higher emissive efficiency and a lower nonradiative decay process compared with βCB and γCB. Interestingly, the crystalline powders of αCB , including the solvent molecules in its unit cell, demonstrated a high-contrast and reversible mechanochromic phenomenon, which originated from the conversion of the compound from a crystalline state to a randomly aggregated one. The above findings provide insights into the molecular design of carboline-based D‒A‒ D-type organic fluorophores with high emissive efficiency and intriguing functional characteristics. [Display omitted] • The first examples of donor‒acceptor‒donor (D‒A‒D) type α-, β-, and γ-carboline-based benzothiadiazole compounds. • Intramolecular-charge-transfer characteristic via distinct solvatochromic effect and high quantum efficiency. • High-contrast and reversible mechanochromism phenomenon in the process of grinding sample and fuming CHCl 3 vapor. • Insight for molecular design of carboline based D‒A‒D type organic fluorophores. [ABSTRACT FROM AUTHOR]

Three novel BODIPY-based heterodinuclear complexes, [salen(3,5-tBu)2Al-(OC6H4-BODIPY)] (6), [salen(3,5-tBu)2Al-(OC6F2H2-BODIPY)] (7), and [(mq)2Al-(OC6H4-BODIPY)] (8) (salen = N,N′-bis(salicylidene)ethylenediamine, BODIPY = 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene, and mq = methyl-8-quinolinolato) were prepared and characterized by multinuclear NMR spectroscopy. The specific structures of 6–8 were also determined by single crystal X-ray analysis. In particular, the salen-based heterodinuclear complexes 6 and 7 exhibited higher thermal stability (Td5 = 309 and 306 °C, respectively) than that of the closely related mononuclear aluminum or BODIPY compounds, except for 8. The UV/vis absorption and PL spectra for 6 and 7 indicated a significant photoinduced energy transfer from the aluminum–salen moiety to the BODIPY group in an intramolecular manner. Theoretical calculations revealed independent transition states of the aluminum–salen moiety or the BODIPY group in the AlIII–BODIPY dyads, further supporting these experimental results. [ABSTRACT FROM AUTHOR]

A novel Ta(V) tBu-imido/aminoalkoxidecomplex, Ta(NtBu)(dmamp)2Cl (1),was synthesizedby metathesis reaction between Ta(NtBu)Cl3(py)2and 2 equiv of Na(dmamp), and subsequent reaction of 1with 1 equiv of MeLi gave a new tantalum complex, Ta(NtBu)(dmamp)2Me (2). Compounds 1and 2have been characterized by IR, 1H and 13C NMR spectroscopy, and microanalytical data.The molecular structure of 1, determined by X-ray singlecrystallography, revealed distorted octahedral geometry. The behaviorof compound 1in solution was studied by variable-temperature 1H NMR spectra. Thermogravimetric analysis revealed superiorthermal properties of 2as compared to those of 1. [ABSTRACT FROM AUTHOR]