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In the field of perovskite optoelectronics, developing hole-transporting materials (HTMs) on the spiro[fluorene-9,9′-xanthene] (SFX) platform is one of the current research focuses. The SFX inherits the merits of spirobifluorene in terms of the configuration and property, but it is more easily derivatized and regulated by virtue of its binary structure. In this work, we design and synthesize four isomeric SFX-based HTMs, namely m-SFX-mF, p-SFX-mF, m-SFX-oF, and p-SFX-oF, through varying the positions of fluorination on the peripheral aniline units and their substitutions on the SFX core, and the optoelectronic performance of the resulting HTMs is evaluated in both perovskite solar cells (PSCs) and light-emitting diodes (PeLEDs) by the vacuum thermal evaporating hole-transporting layers (HTLs). The HTM p-SFX-oF exhibits an improved power conversion efficiency of 15.21% in an inverted PSC using CH3NH3PbI3 as an absorber, benefiting from the deep HOMO level and good HTL/perovskite interface contact. Meanwhile, the HTM m-SFX-mF provides a maximum external quantum efficiency of 3.15% in CsPb(Br/Cl)3-based PeLEDs, which is attributed to its perched HOMO level and shrunken band-gap for facilitating charge carrier injection and then exciton combination. Through elucidating the synergistic position effect of fluorination on aniline units and their substitutions on the SFX core, this work lays the foundation for developing low-cost and efficient HTMs in the future. [ABSTRACT FROM AUTHOR]

Spiro[fluorene-9,9′-xanthene] (SFX) bipolar hosts bearing one, two and three quinolyl substituents, namely SFX-bPy, SFX-DbPy and SFX-TbPy, were designed and synthesized for phosphorescent organic light emitting diodes (PhOLEDs). The successive substitution of quinoline at 2′, 2 and 7′ positions of SFX results in reduced LUMO energy levels while leaving the HOMO energy levels nearly intact. The impact of quinoline substitution in these SFX-based hosts on PhOLED performance was investigated in detail through green and red model devices. For the green emitting devices, the device based on SFX-bPy host showed better performance (23.6 cd A-1, 23.4 lm W-1, 6.3%) due to high triplet energy level (T1) and balanced carriers-transporting ability. In contrast, for the red PhOLED devices, the device hosted by SFX-DbPy displayed higher performance (15.8 cd A-1, 16.0 lm W-1, 9.1%), attributable to the well matched T1 and separated frontier molecular orbitals. This work thus sheds light on the rational design of SFX-based bipolar hosts for more efficient PhOLEDs.

In view of Hg2+ ion sensing by luminescence, a series of new, phenanthroline-decorated 3D lanthanide metal organic frameworks (Ln-MOFs) valorising an original combination of four different lanthanides and two organic ligands, i.e. thiobis(4-methylene-benzoic acid) (H2tmba) and 1,10-phenanthroline (phen), have been successfully synthesized, namely {[Ln4(tmba)6(phen)4]·m(H2O)(phen)}n [Ln = Ce, m = 3 (1); Pr, m = 1 (2); Eu, m = 3 (3); and Tb, m = 3 (4)]. Compounds 1–4 were characterised by single-crystal X-ray diffraction, elemental and thermogravimetric analyses, and powder X-ray diffraction. The luminescence properties of complexes 3 and 4 were thoroughly investigated. It is herein proved that compound 3 sensitively and selectively acts as an excellent luminescent probe for the detection of Hg2+ ions in waters, with a detection limit of 1.00 μM. As additional assets, 3 displays superb stability over a wide pH range (3–12) of the aqueous media, as well as convenient recycling after completion of the detection experiments. The rationale for the observed luminescence quenching effect of mercury might be a strong interaction arising between Hg2+ ions and the carboxylate oxygen atoms of the tmba2− ligand. The results open new perspectives for applications in environmental remediation. [ABSTRACT FROM AUTHOR]

Pd nanoparticles were immobilized on a highly porous, hydrothermally stable Eu-MOF via solution impregnation and H2 reduction to yield a novel Pd@Eu-MOF nanocatalyst. This composite was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), inductively coupled plasma optical emission spectroscopy (ICP-OES), powder X-ray diffraction (PXRD) and X-ray photoelectron spectroscopy (XPS). Unprecedentedly, the Pd@Eu-MOF nanocatalyst could be applied with excellent results in two strikingly different, mechanistically distinct, reactions i.e., Suzuki–Miyaura cross-coupling and cycloaddition of CO2 to a range of epoxides. Under the best reaction conditions, 98–99% yields have been attained in both catalytic processes. Moreover, in either case the heterogeneous catalyst was easily recovered and efficiently reused for more than four cycles, indicating its high stability and reproducibility. PXRD, TEM and XPS measurements on the recycled catalyst confirmed that it maintained its original structure and morphology; no Pd NP agglomeration was observed. [ABSTRACT FROM AUTHOR]