Largely Color-Tuning Prompt and Delayed Fluorescence: Dinuclear Cu(I) Halide Complexes with tert-Amines and Phosphines.

Luminescent copper(I) halide complexes with bi- and tridentate rigid ligands have gained wide research interests. In this paper, six tetracoordinate dinuclear copper(I) halide complexes, Cu2X2(ppda)2 [ppda = 2-[2-(dimethylamino)phenyl(phenyl)phosphino]-N,N-dimethylaniline, X = I (1), Br (2), Cl (3)] and Cu2X2(pfda)2 [pfda = 2-[2-(dimethylamino)-4-(trifluoromethyl)phenyl(phenyl)phosphino]-N,N-dimethyl-5-trifluoromethylaniline, X = I (4), Br (5), Cl (6)], were successfully prepared and systematically characterized on their structures and photophysical properties. Complexes 1-5 have a centrosymmetric form with a planar Cu2X2 unit, and complex 6 has a mirror symmetry form with a butterfly-shaped Cu2X2. Solid complexes 1, 4, and 5 emit delayed fluorescence at room temperature, intense blue to greenish yellow (λmax = 443-570 nm) light, and their peak wavelengths are located at 443-570 nm with microsecond lifetimes (τ = 0.4-19.2 µs, ΦPL = 0.05-0.48). Complexes 2, 3, and 6 show prompt fluorescence, very weak yellowish green to yellow (λmax = 534-595 nm) emission with peak wavelengths at 534-595 nm, and lifetimes in nanoseconds (τ = 4.4-9.3 ns, ΦPL < 0.0001). (Metal + halide) to ligand and intraligand charge transitions are the main origin of the emission of the complexes. Solution-processed, complex-4-based nondoped and doped devices emit yellow green light with CIE coordinated at (0.41, 0.51), a maximum EQE up to 0.17%, and luminance reaching 75.52 cd/m2.

From a blue to white to yellow emitter: a hexanuclear copper iodide nanocluster.

Highly emissive copper(i) halide nanoclusters showing thermally activated delayed fluorescence (TADF) have been paid much attention, but rarely reported so far. Herein, a hexanuclear copper(i) iodide cluster containing a tridentate N∧P∧N ligand, [Cu6I6(ppda)2] {ppda = 2-[2-(dimethylamino)phenyl(phenyl)phosphino]-N,N-dimethylaniline}, was synthesized. All six copper atoms are four-coordinate, including four CuPNI2 and two CuI4 units. This complex exhibits intense white emission in the powder state at room temperature and shows a peak at a wavelength of 535 nm (ΦPL = 0.36) with a microsecond lifetime (τ = 4.4 µs). Emission colors can be largely tuned from blue to white to yellow, from the crystal to powder to film state at 297 K. The emission of [Cu6I6(ppda)2] originates from a combination of MLCT and XLCT transitions. This complex showed good thermal stability. A solution-processed, nondoped device of complex [Cu6I6(ppda)2] exhibits stable yellow emission with the CIE coordinates (x, y) of (0.43, 0.51). [Cu6I6(ppda)2] also shows reasonable photocatalytic H2 evolution activity under visible-light irradiation.

An automatic measurement method of spinal curvature on ultrasound coronal images in adolescent idiopathic scoliosis.

This study proposed a new automatic measurement method of spinal curvature on ultrasound coronal images in adolescent idiopathic scoliosis (AIS). After preprocessing of Gaussian enhancement, the symmetric information of the image was extracted using the phase congruency. Then bony features were segmented from the soft tissues and background using the greyscale polarity. The morphological methods of image erosion and top-bottom-hat transformation, and geometric moment were utilized to identify the spinous column profile from the transverse processes. Finally, the spine deformity curve was obtained using robust regression. In-vivo experiments based on AIS patients were performed to evaluate the performance of the developed method. The comparison results revealed there was a significant correlation (y=0.81x, r=0.86) and good agreement between the new automatic method and the manual measurement method. It can be expected that this novel method may help to provide effective and objective deformity assessment method during the ultrasound scanning for AIS patients.

From deep blue to green emitting and ultralong fluorescent copper(i) halide complexes containing dimethylthiophene diphosphine and PPh3 ligands.

Highly emissive copper(i) halide complexes having thermally activated delayed fluorescence (TADF) have been paid much attention. Here, a series of four-coordinate mononuclear copper(i) halide complexes containing both bi- and mono-phosphine ligands, [CuX(dpmt)(PPh3)] (dpmt = 3,4-bis(diphenylphosphino)-2,5-dimethylthiophene, X = I (1), Br (2) and Cl (3)), were synthesized, and their molecular structures and photophysical properties were investigated. These complexes exhibit intense deep blue emission in crystal state at room temperature and have peak wavelengths at 447-460 nm with microsecond lifetimes (τ = 114-752 µs). Emission color can be largely tuned from deep blue to green, from crystal to film state at 293 K. The emission of the complexes 1-3 mainly originates from intraligand and LLCT transitions. Solution-processed, nondoped and doped devices of complex 3 exhibit yellowish green emission with CIE(x, y) of (0.3557, 0.5031). The nondoped device gives a maximum external quantum efficiency (EQE) of 2.47% and a maximum luminance of 316 cd m-2.

Near-saturated red emitters: four-coordinate copper(i) halide complexes containing 8-(diphenylphosphino)quinoline and 1-(diphenylphosphino)naphthalene ligands.

Recently, highly emissive neutral copper halide complexes have received much attention. Here, a series of four-coordinate mononuclear Cu(i) halide complexes, [CuX(dpqu)(dpna)] (dpqu = 8-(diphenylphosphino)quinoline, dpna = 1-(diphenylphosphino)naphthalene, X = I (1), Br (2) and Cl (3)), were synthesized, and their molecular structures and photophysical properties were investigated. These complexes exhibit near-saturated red emission in the solid state at room temperature and have peak emission wavelengths at 669-691 nm with microsecond lifetimes (τ = 0.46-1.80 µs). Small S1-T1 energy gaps in the solid state indicate that the emission occurs from a thermally activated excited singlet state at ambient temperature. The emission of the complexes 1-3 mainly originates from MLCT transition. The solution-processed devices of complex 1 exhibit stable red emission with a CIE(x, y) of (0.62, 0.38) for a doped device and (0.63, 0.37) for a non-doped device.

Stereoselective synthesis of N-ethyl-2-arylvinyl-5-methyl fulleropyrrolidines: reaction of [60]fullerene with aromatic aldehydes and triethylamine/diethylamine in the absence or presence of manganese(iii) acetate.

The reaction of [60]fullerene with aromatic aldehydes and triethylamine/diethylamine in the absence or presence of manganese(iii) acetate under air conditions afforded a series of N-ethyl-2-arylvinyl-5-methyl fulleropyrrolidines in moderate to good yields, which would be difficult to synthesize by reported protocols. The in situ generation of arylvinyl aldehydes by the aldol reaction of aromatic aldehydes with acetaldehyde from an unusual C-N bond cleavage of triethylamine/diethylamine played a crucial role in the successful preparation of the corresponding fulleropyrrolidines. Depending on the reaction conditions, both cis and trans isomers of fulleropyrrolidines could be selectively synthesized. Cis isomers as major products could be obtained by reacting with triethylamine at 160 °C without the addition of manganese(iii) acetate, while trans isomers as major products, with rare exceptions, could be observed via the reaction with diethylamine at 120 °C under the assistance of manganese(iii) acetate. Moreover, the in situ generated arylvinyl aldehydes displayed higher reactivity towards diethylamine as compared with aryl aldehydes, leading to the formation of arylvinyl-substituted fulleropyrrolidines. A plausible formation mechanism for fulleropyrrolidines was provided based on the experimental observations.

Synthesis of 2-Aryl-5-alkyl-fulleropyrrolidines: Metal-Free-Mediated Reaction of [60]Fullerene with Aromatic Aldehydes and Inactive Primary Amines.

The metal-free-mediated thermal reaction of [60]fullerene with aromatic aldehydes and inactive primary amines bearing electron-donating groups at the α-position afforded a series of 2-aryl-5-alkyl-fulleropyrrolidines, including the scarce 2-aryl-5-benzyl-fulleropyrrolidines as a mixture of cis and trans isomers. With rare exceptions, the mixture of cis and trans isomers could be easily isolated by column chromatography, with a preference of cis isomers as major products. A plausible mechanism for the formation of fulleropyrrolidines is also proposed.

A Protocol for the Preparation of 2,5-Diaryl Fulleropyrrolidines: Thermal Reaction of [60]Fullerene with Aromatic Aldehydes and Arylmethanamines.

Thermal reaction of [60]fullerene with various arylmethanamines in the presence of aromatic aldehydes under air conditions afforded a series of rare 2,5-diaryl fulleropyrrolidines. Intriguingly, the obtained fulleropyrrolidines exhibited different stereoselectivity. N-unsubstituted arylmethanamines exclusively produced 2,5-diaryl fulleropyrrolidines as cis isomers, while N-substituted arylmethanamines with rare exceptions always gave 2,5-diaryl fulleropyrrolidines as trans isomers. Theoretical calculations at the level of B3LYP/6-31G (d,p) were employed to elucidate the stereoselectivity of N-substituted 2,5-diaryl fulleropyrrolidines as trans isomers by investigating the transition-state structures of different cycloaddition pathways.