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The synthesis of four novel seven-member-ring-based electron-transporting materials with high thermal stability and the fabrication of high-performance OLED devices using the same are reported.

N-Hydroxy-p-(4-arylbutanamido)benzamides (HABAB) belong to one class of histone deacetylase inhibitors (HDACi), which regulate deacetylation of lysine residue’s amino group in histone, which result...

High-valent chiral oxidovanadium(V) complexes derived from 3,5-substituted-N-salicylidene-l-tert-leucine were used as catalysts in asymmetric reduction of N-benzyl-β-ketoamides. Among six different solvents, three different alcohol additives, and two different boranes examined, the use of pinacolborane in tetrahydrofuran (THF) with a t-BuOH additive led to the best results at -20 °C. The corresponding β-hydroxyamides can be furnished with yields up to 92% and an enantiomeric excess (ee) up to 99%. We have successfully extended this catalytic protocol for the synthesis of an (S)-duloxetine precursor.

A catalytic protocol for “CF3”-radical type addition to terminal and β-substituted olefins with Togni’s reagent to deliver various α-trifluoromethylated ketones of biomedicinal interests was examin...

Chemoselective enantiodivergent reduction of N-benzyl-α-keto amides catalyzed by chiral oxido-vanadium(V) complexes derived from a reduced form of N-salicylidene L-tert leucinate can be achieved with good yields and good to high enantioselectivities. These chiral complexes were utilized in catalyzing the enantioselective synthesis of (R)-N-benzyl-mandelamide with pinacolborane and (S)-N-benzyl-mandelamide with catecholborane from the corresponding ketone precursors. A series of 12 different solvents and 8 different reducing agents were examined. By the use of pinacolborane (R isomer, 74–99% ee) or catecholborane (S isomer, 60–90% ee), a handy approach for complementary asymmetric reduction of α-keto amides can be attained.

The 1-aryl tetrahydroisoquinolines (1-aryl THIQs) are omnipresent in biologically active molecules. Here we report on the direct asymmetric synthesis of these valuable compounds via the reaction of 3,4-dihydroisoquinolinium tetraarylborates. The dual roles of anionic tetraarylborates, which function as both prenucleophiles and stabilizers of 3,4-dihydroisoquinolinium cations, enable this rhodium(I)-catalyzed protocol to convergently provide enantioenriched 1-aryl THIQs in good yields (≤95%) with ≤97% ee, as demonstrated by the formal synthesis of (-)-solifenacin and the facile synthesis of (-)-Cryptostyline I.

Directed assembly of loosely, Na+-bound, oxidovanadate-centered quartets of C4-symmetry from tailor-made chiral N-salicylidene-vanadyl(V) complexes, for the first time, allows for highly efficient Ba2+- or Hg2+-specific detection (by 51V NMR and VCD), transport (forming a unique helical capsule or a capped square planar complex, respectively), and green recovery from an aqueous phase containing 4 different alkaline earth ions or from at least 10 different metal ions of similar size and charge capacity into the CHCl3 layer without interference from oxa- or oxophilic ions like Mg2+, Ca2+, Cu2+, Cd2+, and Pb2+.

This article reports for the time-resolved photophysical studies of spirally configured ( cis-stilbene) trimers and their spin-coated organic light-emitting diode (OLED) device performances. Transient absorption profiles of spirally configured, ter-( cis-stilbene) were studied by pulse radiolysis. The emission profiles after charge recombination of their incipient radical ions in benzene provides insights into the emission mechanism and efficiency in OLED devices. Blue-, sky blue-, and green-emitting OLED devices for a maximum external quantum efficiency are 4.32%, 4.70%, and 2.77%, respectively, by solution process.

A spiro core appended with trithiophene arms and α-cyanoacrylate end groups was used for the first time in bulk heterojunction solar cell applications. The resulting device performance was evaluated by its blending with PC61BM, leading to a short-circuit current density (Jsc) of 3.55 mA cm–2 which was 2.4 and 6.6 times better than those of the open form and nonspiro core analogs. The 1,8-diiodooctane solvent additive suppressed its microcrystalline self-aggregation, leading to a well-defined blend film morphology with reduced domain size and thus enhanced Jsc to 6.14 mA cm–2 and fill factor to 67.2% by 70% and 135% increase, respectively. The film domain size can be further reduced to 50 nm by its blending with PC71BM, leading to a PCE of 4.87% with an improved Jsc of 7.93 mA cm–2, a Voc of 0.97 V, and a fill factor of 64.1%.

A pseudo-enantiomeric pair of optically switchable helicenes containing a catalytic 4-N-methylaminopyridine (MAP) bottom unit and a C2-symmetric, (10R,11R)-dimethoxymethyl-dibenzosuberane top template was synthesized. They underwent complementary photoswitching at 290 nm (P/M′, 99) and 340 nm (P/M′, 91/9) and unidirectional thermo-rotation at 130 °C (P/M′, >99/

Solution processing enables organic devices to be fabricated cost-effectively, while deep-red emitters enable displays with high color saturation and lighting with high light quality. However, limited deep-red emitters were reported with solution-process feasibility and high efficiency. We demonstrate here a high-efficiency, solution-process-feasible deep-red emitter by coupling the highly efficient phosphorescent complex with a highly thermally stable fluorescent compound. The device exhibits a maximum external quantum efficiency of 11.2% at 10 cd m–2 and 8.4% at 100 cd m–2. The latter is coupled with an ultradeep red emission (0.70, 0.27) and a potential color saturation of 108%. Besides the intrinsically high-efficiency nature of the phosphorescent complex, the record high efficiency may be attributable to the spirally configured fluorene moiety in the fluorescent compound to prevent concentration-quenching effect, a proper host to enable an effective host-to-guest energy transfer, and the employed coh...

A bright orange–red organic light-emitting diode (OLED) with an extraordinarily high external quantum efficiency (EQE) was achieved by using a seven-member-ring based fluorescent emitter with a matching host. The emitter, 3-(N,N-diphenylamino)-7-(β,β-dicyanoethenyl)-5,5-spirofluorenyl-5H-dibenzo[a,d]-cycloheptene, was composed of a spirally configured cis-stilbene/fluorene moiety with an ambipolar character, and the matching host was 1-butyl-9,10-naphthalene-anthracene (BANE). An orange–red emission peaking at 617 nm with an EQE continuously rolling up to its observable maximum luminance was obtained as a 1.5 wt% of the red emitter was doped into the BANE host. For examples, the EQEs were increased from 5.01 ± 0.015% to 5.76 ± 0.02%, and 6.43 ± 0.04% as the luminance was increased from 10,000 to 15,000 and 20,000 cd/m2, respectively. The high efficiency at high brightness as well as an unusual efficacy roll-up may be attributed to both the efficiency-effective device architectural factors, including low injection barriers, balanced carrier injection, effective host-to-guest energy transfer, and effective exciton generation on both host and guest, and the ambipolar emitter that showed an increasing balance in carrier injection as the applied voltage continued to increase.

We demonstrate the feasibility of bringing the sunset hue indoors via a dusk-light-style organic light emitting diode that exhibits a color temperature ranging between 1500 and 3000 K, covering that of sunset hue within the last 30 min before sunset. Like the sunset, the device chromaticity changes from yellowish white to reddish orange, with illuminance decreasing by 60-fold as the color temperature decreases from 2900 to 2100 K. The artificial dusk hue at 2745 K, for example, shows a 92 color rendering index with an 87% luminance spectrum resemblance with the sunset hue. The very high color rendering character is obtained by depositing phosphorescent red and yellow dyes in one emission layer and a fluorescent green dye doped into a fluorescent blue light emitting host in another, separated by a nanoscale carrier modulation interlayer to harvest the ultimate color rendering index and minimize the color temperature.

Yellow emission is crucial in RGBY display technology and in fabricating physiologically friendly, low color-temperature lighting sources. Emitters with both wet- and dry-process feasibility are highly desirable to fabricate, respectively, high-quality devices via vapor deposition and cost-effective, large-area devices via roll-to-roll fabrication. Here, high-efficiency organic light-emitting diodes with a novel wet- and dry-process feasible yellow-emitting iridium complex, bis[5-methyl-7-fluoro-5H-benzo(c)(1,5) naphthyridin-6-one]iridium (picolinate), are demonstrated. By spin coating, the device shows, at 1000 cd m−2, an external quantum efficiency (EQE) of 18.5% with an efficacy of 52.3 lm W−1, the highest among all reported yellow devices via wet-process, while using vapor deposition, the EQE is 22.6% with a 75.1 lm W−1 efficacy, the highest among all dry-processed counterparts. The high efficiency may be attributed to the replacement of the hydrogen atom with a fluorine atom on a 2-substitutional site in the emitter to prevent dense molecular packing-caused self-quenching and to reduce radiationless deactivation rates, leading to a high quantum yield (71%).

High efficiency green emission is crucial to the designs of energy-saving display and lighting. Efficient electroluminescent green emitters with both wet- and dry-process feasibility is highly desirable in order to realize, respectively, cost-effective large roll-to-roll manufacturing and high performance products. In this study, high-efficiency, phosphorescent, green organic light emitting diodes with a novel iridium complex, bis[5-methyl-8-trifluoromethyl-5H-benzo(c)(1,5)naphthyridin-6-one] iridium (acetylacetonate), are demonstrated. They possess both wet- and dry-processing possibilities. The emitter exhibits a short excited-state lifetime, 1.25 μs, and a high quantum yield, 69%, due to the efficient intersystem crossing of the ground state to the excited state. Using 4,4′-bis(carbazol-9-yl)biphenyl as a host, the device shows at 1000 cd m−2 an external quantum efficiency (EQE) of 21% and power efficiency of 64 lm W−1 via vapor deposition, while 26% EQE and 69 lm W−1 by spin-coating, the highest among all reported wet-processed green organic light emitting diodes. Besides electroluminescence, the high device efficiency may also be attributed to the employed device architecture enabling therein an electron trap to facilitate the injection of this minor carrier against that of a hole, leading to a balanced carrier-injection, and hence a high carrier recombination and in turn a high device efficiency.

A gallamide-containing pseudoenantiomeric helicene pair bearing a (10R,11R)-dimethoxymethyldibenzosuberane core can self-assemble by intermolecular amide H-bonding and π-π stacking into bundled helical fibers with helical tunnels of complementary helicity in CH2Cl2. The helicenes undergo excellent complementary photoswitchings of ternary logic at 280, 318, and 343 nm through (-)-gel-sol-(+)-gel interconversion.

Light sources with lower color temperature (CT) show markedly less suppression effect on the secretion of melatonin, an oncostatic hormone. Light sources with higher color rendering index (CRI) provide better visual comfort. In this report, we demonstrate the design and fabrication of low CT, high CRI fluorescent organic light-emitting diode (OLED) with five-band emitting from a single emissive layer. The best performed device exhibits a CT of 1773 K, much lower than that of candles (1800–2000 K) or incandescent bulbs (2000–2500 K), 87 CRI, a beyond theoretical limit external quantum efficiency (EQE) 6.4%, and 11.9 lm/W at 100 cd/m 2 . One major reason for having the ultra-low CT and relative high CRI may be attributed to the significantly intensive deep red emission. The comparatively high efficacy and EQE may be attributed to the employment of a smooth stepwise energy-level structure, enabling low injection barriers and balance carrier injection.

Among five different oxidometallic species and two Lewis acids investigated, MoO 2 Cl 2 shows the best catalytic and chemoselective activity for the deacylation of esters in methanol at ambient or elevated temperature. Both high efficiency and chemoselectivity were achieved for substrates bearing different ether or ester groups. Acylated mono and disaccharides can also be selectively deacetylated in good yields, leading to useful carbohydrate templates for further synthetic manipulations.

The fluorescent dye Cy3 and galactose derivatives are covalently assembled with different ratios on the surfaces of magnetic nanoparticles (MNPs) to produce multifunctional HepG2 cancer cell–targeting agents and the effect of ligand spatial orientation on the MNP surface is investigated on targeting specificity. By using a mixture of bis-N-hydroxysuccinimide ester (a bifunctional linker) and OSu-activated Cy3 (w/w = 30:1), stable and quantifiable fluorescent MNPs (Cy3@MNPs) are synthesized that could be subsequently loaded with galactosyl ligands. A mono-antennary and two different tri-antennary galactosyl ligands are individually immobilized on Cy3@MNPs, and the uptake efficiencies of the resulting galactosyl Cy3@MNPs by HepG2 and HeLa cells are investigated using confocal microscopy. The confocal images show that galactosyl Cy3@MNPs are sprayed over cytoplasm of the HepG2 cells, indicating that the MNP uptake occurs via receptor-mediated endocytosis that is followed by release from endosomes. The results also reveal that the ligand spatial orientation affects the efficiency of the receptor-mediated endocytosis and one of the tri-antennary galactosyl ligands shows the best uptake efficiency owing to the optimal spatial presentation of the galactosyl moieties. Overall, it is shown that the MNP is a good ligand carrier and that, when pre-assembled, the multivalent ligand structure enhances the interactions between the surface ligands of the MNPs and receptors of HepG2 cells. Additionally, the galactosyl Cy3@MNPs are not cytotoxic, indicating that they may potentially be used for in vivo applications.

Among 14 oxidometallic species examined for catalytic phosphorylation of the tested alcohols, oxidomolybdenum tetrachloride (MoOCl 4 ) was found to be the most efficient with a negligible background reaction mediated by triethylamine (Et 3 N). The new catalytic protocol can be applied to the chemoselective phosphorylations of primary, secondary and tertiary alcohols as well as the substitution-free phosphorylations of allylic, propargylic, and benzylic alcohols. Functionalized alcohols bearing acetonide, tetrahydropyranyl ether, tert-butyldimethylsilyl ether, or ester group are also amenable to the new catalytic protocol. The most difficult scenarios involve substitution-free phosphorylations of 1-phenylethanol and 1-(2-naphthyl)ethanol which can be effected in 95 and 90% yields, respectively. ESI-MS, IR, 1 H, and 31 P NMR spectroscopic analyses of the reaction progress suggest the intermediacy of an alkoxyoxidomolybdenum trichloride-triethylamine adduct such as [(RO)Mo(O)Cl 3 -Et 3 N] to be responsible for the catalytic turnover.

A series of thiols have been examined as protic nucleophiles for Michael-type additions to α,β-unsaturated carbonyls as well as double nucleophilic condensations with aldehydes, ketones, and acetals catalyzed by amphoteric, water-tolerant vanadyl triflate under mild and neutral conditions. The newly developed C–S bond formation protocols were carried out smoothly in good to high yields in a highly chemoselective manner.

A series of bipolar OLED materials were subjected to pulsed radiolysis experiments to determine their transient absorption and lifetime profiles of the independently in situ generated radical cations and anions in solutions. Moreover, their emission behaviors from the charge recombination of their radical ions were also determined by the pulse radiolysis method. It was found the absorption bands in doubly ortho-linked quinoxaline/diphenylfluorene hybrids 1a-e are red-shifted progressively with increasing electron-donating nature at the C5 and C8 positions of the quinoxaline template. The incipient radical anions in 1a-e are mainly localized on the quinoxaline heterocyclic moiety, whereas the incipient radical cations are mainly distributed onto the attached electron-donating groups at the C5 and C8 positions of the quinoxaline template. For other doubly ortho-linked cis-stilbene derivatives 3d, 3f, and 4f, the radical anions are mainly localized on the cis-stilbene central moiety and the radical cation is mainly distributed onto both para substituents of the cis-stilbene templates. It was also shown that there is a correlation between their optoelectronic emission efficiencies and the radiolysis induced emission intensities. In addition, the charge transporting behaviors within an OLED device were found to show the relationship with transient absorption half-lives (tau(1/2)) of the radical ions. Charge recombination mechanisms in both the OLED and pulsed radiolysis experiments were proposed to rationalize these observations, allowing us to establish some guidelines for an ultimate molecular design of ideal bipolar optoelectronic materials with a judicious choice of local charge appendages in the optoelectronic templates.

The nuclearity of two previously prepared nickel complexes, [LNiCl(μ-Cl)]2·2CH3OH (1) and L′NiCl2 (2) (L = bis(1-methylbenzimidazoyl-2-methyl)amine and L′ = bis(1-methylbenzimidazoyl-2-methyl)-10-camphorsulfonamide), was found to be temperature-dependent. Mononuclear [LNi(CH3OH)2Cl]Cl·2H2O (3) and dinuclear [L′NiCl(μ-Cl)]2 (4) were obtained as crystals at −20 °C. It is noteworthy that complex 2 can catalyze the conjugate addition of thiophenols to α,β-enones in high yields; in contrast, the same reaction catalyzed by NiCl2·THF or complex 3 was far less effective.

A new tri-antennary, galactoside-capped gallamide dendritic anchor with thiolate focal group is synthesized via click chemistry. The highly hydrophilic dendron was efficiently anchored onto the surface of CdSe/ZnS core/shell nanoparticles in a covalent fashion, as evidenced by 1 H NMR spectrum of the resultant nanohybrid with intact core fluorescent property. The water-soluble nano-hybrid was found smoothly and selectively uptaken by lung cancer cells enriched with membrane-bound asialoprotein receptors in 2-3 h, as evidenced by confocal microscopic analysis. Furthermore, cancer cells that are undergoing active mitosis also tend to uptake the nanohybrids efficiently and remain sustainable in serum-containing medium for several days, which shed light on its application as a photodynamic drug carrier for apoptosis study.

A series of oxometallic species and metal acetylacetonates (acac) was examined as catalysts for oxidative carbonylation of styrene with benzaldehyde using t-butylhydroperoxide as the co-oxidant in warm acetonitrile. Among them, VO((acac)2 and vanadyl(IV) chloride were found to be the only catalyst class to achieve cross-coupling processes by judiciously tuning the ligand electronic attributes, leading to β-hydroxylation- and β-peroxidation-carbonylation of styrene, respectively, in a complementary manner. Mechanistic studies indicated that vanadyl-associated acyl radicals generated by t-butoxy radical-assisted, homolytic cleavage of the aldehyde C-H bond were involved in tandem processes with an exclusive syn diastereoselectivity in the case of β-methylstyrene.

A series of oxometallic species and metal acetylacetonates (acac) was examined as catalysts for oxidative carbonylation of styrene with benzaldehyde using t-butylhydroperoxide as the co-oxidant in warm acetonitrile. Among them, VO((acac)2 and vanadyl(IV) chloride were found to be the only catalyst class to achieve cross-coupling processes by judiciously tuning the ligand electronic attributes, leading to β-hydroxylation- and β-peroxidation-carbonylation of styrene, respectively, in a complementary manner. Mechanistic studies indicated that vanadyl-associated acyl radicals generated by t-butoxy radical-assisted, homolytic cleavage of the aldehyde C-H bond were involved in tandem processes with an exclusive syn diastereoselectivity in the case of β-methylstyrene.

Lithium perchlorate is demonstrated to be a highly efficient and convenient catalyst for the per-O-acetylation of various saccharides with excellent yields.

[reaction: see text] A series of oxovanadium(IV) complexes derived from tridentate N-ketopinidene-alpha-amino acids were synthesized. They serve as efficient catalysts for the enantioselective oxidative couplings of various 3-, 6-, or 7-substituted 2-naphthols. The best scenario involves the use of a vanadyl complex arising from L-tert-leucine in CCl4. The asymmetric couplings of 2-naphthols can be conducted smoothly at 40-45 degrees C under a stream of gaseous oxygen, leading to 2,2'-dihydroxy-1,1'-binaphthyls in good yields (61-99%) and with enantioselectivities of up to 87%.

[reaction--see text] Among four vanadyl species examined, vanadyl triflate was the most efficient catalyst to facilitate nucleophilic acyl substitution of anhydrides with a myriad array of alcohols, amines, and thiols in high yields and high chemoselectivity. By using mixed-anhydride technique, one can achieve oleate and peptide syntheses. In marked contrast to common metal triflates, the amphoteric character of the V=O unit in vanadyl species was proven to be responsible for the catalytic profile in this process.

Three C2-symmetric (10R,11R)-diethyl substituted dibenzosuberane (DBS)-based helicenes with varying steric and conjugation demands of their bottom fragments were synthesized. The X-ray analyses of their precursors-episulfides reveal the preferred conformation of the DBS skeleton possessing equatorially oriented ethyl groups at C-8 and C-9 positions. In all cases, the absolute configuration in the episulfide moiety is S, which can lead stereospecifically to the corresponding P helicenes after the reductive desulfurization of the episulfides. Only the helicene-7a with the bottom part derived from α-tetralone was found photoswitchable in reasonable time scale. Photoisomerization of the diastereomerically pure (10R,11R,P)-helicene (7a) at 280 nm led to virtually exclusive formation of the opposite M form-diastereomer 7a‘ (7a‘/7a = 99.6/0.4). The preferential return of 7a‘ to 7a can be effected upon irradiation at 254 nm (7a‘/7a = 33/67) or thermally at 130 °C (7a‘/7a = 0/100). The photoinduced switching proce...

A diverse array of oxometallic species were examined as catalysts for a test direct condensation of benzoic acid and 2-phenylethanol in 1:1 stoichiometry. Besides group IVB MOCl2-xH2O and TiOX2-xH2O, group VB VOCl2-xTHF and group IVB TiO(acac)2 were found to be the most efficient and water-tolerant catalysts for the test reaction. The new neutral catalytic protocol with the optimal TiO(acac)2 tolerates many stereo/electronic structural variations in both (di)acid (1 degree -3 degrees alkyl and aryl) and (di)alcohol (1 degree, 2 degrees alkyl, and aryl) components with high chemoselectivity.