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Two tritylthio-based compounds were synthesized: 1-bromo-3-tritylthiopropane 1 and 2-(tritylthio)-ethanethiol 2. They were characterized by infrared, NMR, UV-Vis absorption and fluorescence spectroscopy and single-crystal X-ray diffraction. The crystals of both compounds crystallize in the monoclinic space group P2/ c. The unit cell dimensions of 1 are a = 7.4072 (9) Å, b = 9.6924 (11) Å, c = 25.652(3) Å, β = 90.023 (2), and V = 1841.7 (4) Å, and of 2 are a = 15.3532 (8) Å, b = 14.1552 (7), c = 7.8249 (4) Å, β = 94.5239 (8), and V = 1695.27 (15) Å. The packing structures of 1 and 2 are supported by weak π−π and hydrogen bond interactions. Both 1 and 2 have absorption maxima at 257 nm, and emission maxima at 314 nm and 313 nm, respectively. The compounds differ by the presence of the S-H stretching vibration at ~ 2550 cm in 2 and its absence in 1, as observed in the infrared spectra. Graphical Abstract: Thermal ellipsoid plots of compounds 1 and 2, with thermal ellipsoids at 50% probability. [ABSTRACT FROM AUTHOR]

The design of a relatively simple and efficient method to extend the π-conjugation of readily available aromatics in one-dimension is of significant value. In this paper, pyrenes, peropyrenes, and teropyrenes were synthesized through a double or quadruple benzannulation reaction of alkynes promoted by Brønsted acid. This novel method does not involve cyclodehydrogenation (oxidative aryl-aryl coupling) to arrive at the newly incorporated large arene moieties. All of the target compounds were synthesized in moderate to good yields and were fully characterized with the structures unambiguously confirmed by X-ray crystallography. As expected, photophysical characterization clearly shows increasing red-shifts as a function of extended conjugation within the fused ring systems. [ABSTRACT FROM AUTHOR]

The ligands 4-fluorobenzoate (4-fba), 4-chlorobenzoate (4-cba), 4-bromobenzoate (4-bba) and 4-iodobenzoate (4-iba) were chosen in order to synthesize europium(iii), gadolinium(iii) and terbium(iii) complexes and compare the effect of halogens on their physical chemistry and luminescent properties. The homobimetallic complex [Eu(4-iba)3(H2O)(dmf)]2 crystallizes in the monoclinic P21/c space group with unit cell parameters a = 8.3987(9) Å, b = 25.314(3) Å, c = 14.1255(17) Å, and β = 105.347(2)°. FTIR spectroscopy indicates that the bidentate bridging mode of the carboxylato ligand was present in all complexes while bidentate chelate and a mixture of bidentate bridging and chelate modes were also found. According to emission spectra profiles and the Judd–Ofelt parameters the halogen of ligand molecules modifies the chemical environment symmetry around the europium(iii) ion in their respective complexes. The complexes [Eu(4-fba)3(H2O)2] and [Eu(4-iba)3(H2O)2] have the highest symmetry around the europium(iii) while the complexes [Eu(4-cba)3]·2H2O, [Eu(4-bba)3]·5/2H2O and [Eu(4-iba)3(H2O)(dmf)]2 have the lowest. The different halogens at the para position do not change the covalence degree of Eu–O bonds significantly, however they play a role in the ligand to metal charge transfer energies. The highest non-radiative energy transfer rates from ligand to europium(iii) were found for the complexes [Eu(4-cba)3]·2H2O and [Eu(4-bba)3]·5/2H2O. [ABSTRACT FROM AUTHOR]

A new water-soluble Pybox ligand, 1, has been synthesized and found to crystallize in the monoclinic P21/n space group with unit cell parameters a = 6.0936(1) Å, b = 20.5265(4) Å, c = 12.0548(2) Å, and β = 90.614(1)°. In the crystal, a water molecule is bound through hydrogen-bonding interactions to the nitrogen atoms of the oxazoline rings. This ligand was used to complex a variety of lanthanide ions, opening up new avenues for luminescence and catalysis in aqueous environment. These complexes are highly luminescent in aqueous solutions, in acetonitrile, and in the solid state. Aqueous quantum yields are high at 30.4% for Eu(III), 26.4% for Tb(III), 0.32% for Yb(III), and 0.11% for Nd(III). Er(III) did not luminesce in water, but an emission efficiency of 0.20% could be measured in D2O. Aqueous emission lifetimes were also determined for the visible emitting lanthanide ions and are 1.61 ms for Eu(III) and 1.78 ms for Tb(III). Comparing emission lifetimes in deuterated and nondeuterated water indicates that no water molecules are coordinated to the metal ion. Speciation studies show that three species form successively in solution and the log β values are 5.3, 9.6, and 13.8 for Eu(III) and 5.3, 9.2, and 12.7 for Tb(III) for 1:1, 2:1, and 3:1 ligand to metal ratios, respectively. [ABSTRACT FROM AUTHOR]

We synthesized CDs that were crystalline and monodisperse with average diameters in the range 4–5 nm. The CDs had a fluorescence quantum yield of 0.20%, with emission lifetimes of 3.1 and 6.5 ns attributed to surface and core emissions, respectively. 13 C NMR spectroscopy indicated the presence of C–C, C˭C and C˭O groups on the surface of the CDs. Powder XRD and TEM indicate the CDs are graphitic. The CDs were decorated with Ln III ions through coordination to the surface carbonyl and carboxylato groups. When excited, the CDs transferred energy to the emissive states of the Ln III ions, which led to observation of the characteristic emission spectra of Eu III and Tb III with emission lifetimes of 1.00 and 0.63 ms, respectively and with emission quantum yields of 0.17% and 1.43%, respectively. [ABSTRACT FROM AUTHOR]