Volume 95, Issue 6

Supramolecular gels are generally formed by the self-assembly of organic molecules called low-molecular-weight gelators. However, supramolecular gels can also be formed with the assistance of metal ions. These organic-inorganic hybrids are key for creating highly functional materials. Unique properties and functions that cannot be obtained from organic molecules alone are observed in the metal ion containing supramolecular gels. In this study, several examples of supramolecular gels formed with the assistance of metal ions, cholesterol derivatives, amino acids and peptides, nucleic acid derivatives, oxalic acid, and C 3 -symmetric tris-urea derivatives are introduced. This provides an overview of existing supramolecular gels to better understand the scope for possible future research for their practical applications.

Over the past decades, zinc oxide semiconductor and its derivatives have been extensively developed because of its optoelectronic properties. Since ZnO is an intrinsic n-type semiconductor, how to synthesize high-quality p-type ZnO semiconductors and investigate their optoelectronic properties and local chemical structures are important and necessary. In this article, two studies of synthesizing both undoped and phosphorus-doped ZnO nanostructures by hydrothermal method and chemical vapor deposition (CVD) technique are presented. Scanning electron microscopy (SEM) and laboratory X-ray diffraction (XRD) are used to track the surface morphology and the crystalline structure of both undoped and phosphorus doped ZnO nanostructures, respectively. X-ray absorption near edge structures (XANES), X-ray emission spectroscopy (XES) and X-ray excited optical luminescence (XEOL) are also used to determine the local chemical information of both undoped and phosphorus-doped ZnO nano/microstructures such as local symmetry and optical properties. It is found that the phosphorus is successfully doped into the surface of ZnO and substituted the Zn. The phosphorus-doped ZnO products have better crystallinity and less oxygen vacancies on the surface. These two are correlated as one leads to the other. The XEOL results suggest that the average bandgap for undoped and phosphorus doped ZnO is the same, 3.24 eV. The second derivative of the absorption-emission spectra yields the fundamental bandgap for undoped ZnO and phosphorus-doped ZnO is 3.25 eV. The implication of this observation is discussed.

The synthesis of ultrafine well-dispersed bimetallic RuM (M: Co, Ni, Cu) nanoparticles (NPs) supported on graphene hydrogel (GH) was accomplished by a novel one-pot wet-chemical protocol that comprised the hydrothermal reduction of the mixture of graphene oxide and metal precursors by ethylene glycol (EG) in a Teflon-coated stainless-steel reactor at 180 °C. In this study, for the first time, we report the synthesis of bimetallic RuM NPs anchored on GH during the hydrothermal production of GH from graphene oxide (GH-RuM) and the catalysis of the yielded GH-Ru in the hydrolysis of ammonia borane (AB). As-synthesized GH-RuM (M: Co, Ni, Cu) nanocatalysts were characterized by using many advanced instrumental techniques including TEM, XRD, XPS, and ICP-MS. The bimetallic catalysts denoted as GH-Ru 20 Co 80 , GH-Ru 30 Ni 70 and GH-Ru 10 Cu 90 exhibited much higher catalytic activity compared to their Ru, Co, Ni and Cu monometallic counterparts in the hydrolytic dehydrogenation of AB. The catalytic performance of as-prepared NPs in terms of hydrogen generation rate (HGR) was achieved in the order of RuCo > RuNi > RuCu and the highest HGR calculated for the catalyst GH-Ru 20 Co 80 reached 8911.5 mL H 2  g cat −1  min −1 at room temperature with an activation energy of 52.5 kJ mol −1 .

Theoretical calculations are proving as an essential tool to understand luminescence processes even for systems including lanthanide (Ln 3+ ) ions. As such, the aim of this study is that of presenting a general and comprehensive theoretical protocol based on DFT calculations to rationalize and possibly drive the design of new luminescent Ln 3+ complexes through the ab initio determination of the electronic properties of a ligand and two Eu 3+ complexes. Different theoretical methodologies have been combined to look into the excited state energies, the luminescence quantum yield, and the energy transfer processes. The protocol has been validated for a β-diketone ligand and two Eu 3+ complexes, which contain, in addition to the main ligand, ethanol or triphenylphosphine oxide. Moreover, by starting from the geometry optimization up to the estimation of the ligands’ singlet and triplet lowest energy states, theoretical results quantitatively agree with luminescence experimental parameters, providing at the same time insights into the different energy transfer processes. The different quantum yields of the two complexes have been correctly reproduced.

Periodicity of elements is the basis of teaching and understanding inorganic chemistry. This review exemplifies simple rules and counting procedures as heuristic algorithms yielding often-dimensionless quantities that, as such or together with auxiliary parameters, allow us to predict not only the stoichiometry and bonding of compounds, but also some of their properties or reactions.

By crystal engineering of molecular magnets, unique magnetic functionalities can be intentionally designed. In this work, we synthesized a novel two-dimensional cyanido-bridged coordination network, [Ni II (pz) 4 ]{[Ni II (pz) 3 ][W V (CN) 8 ]} 2 ·3.5H 2 O ( NiW , pz = pyrazole), which exhibits metamagnetic behavior. NiW has wavy coordination layers created by two differently sized molecular square ladders and exhibits strong intralayer ferromagnetic interactions. Nevertheless, due to the relatively short interlayer distance, NiW shows spontaneous antiferromagnetic ordering below a Néel temperature of 21 K. By applying an external magnetic field, such antiferromagnet can be converted into a ferromagnet with a coercive field of 600 Oe at 2 K, elucidating the metamagnetic behavior of NiW .

This minireview discusses recent advances in transition metal complexes for electrochromic (EC) and electrofluorochromic (EFC) devices. EC and EFC materials can switch their color and photoluminescence, respectively, through electrochemical redox reactions. Transition metal complexes offer promising opportunities due to their molecular design versatility for various optoelectrical properties. The review provides an overview of electrochromism and electrofluorochromism, including performance characterization methods and device fabrication techniques. It highlights EC transition metal complexes that can form thin films suitable for device applications and EFC transition metal complexes that can efficiently tune photoluminescence through electrochemical quenching mechanisms. The review also summarizes advanced functions of EC/EFC transition metal complexes, including large optical contrast, fast response, dual-switching of color and emission, and easy device fabrication, which could lead to low-cost displays. Overall, this review article presents the latest research on transition metal complexes for EC and EFC devices and their potential for practical applications.

The ff transition of lanthanide ions such as Eu in the complex appears as unique energy relaxation process as luminescence after the intramolecular energy transfer from the photo-excitation of the ligand with π-electronic system. The Langmuir-Blodgett (LB) film consisting of Eu and amphiphilic naphtoic acids (NaphC 15 ) induced the linearly polarized luminescence (LPL) with a medium, stearic acid (SA), to isolate the luminescence component by the layer structure and to keep the softness at the monolayer depositions on the quartz substrate as reported previously. Here, we used a bulky medium, 3-methyl-4-penthadecyl benzoic acid (MPBA), instead of SA, and found the Eu-NaphC 15 in the LB film places more independently resulting in the 4-fold high quantum yields compared with previous system. The structures of LB films of Eu-NaphC 15 with MPBA were elucidated by the measurement of synchrotron XRD and XPS. Various electronic spectra were quantitatively observed to discuss the effect molecular aggregation through much/less ππ-interaction of NaphC 15 for the intensified LPL in the films.