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We report the syntheses and catalytic activity of a series of piano-stool iron complexes with the general formula [FeClCp*(NHC)] (where NHC = N-heterocyclic carbene) toward the gem-specific dimerization of terminal alkynes. In comparison to our first-generation catalyst, the newly synthesized catalyst is more active and features the same geminal specificity. Both the experimental and computational data are presented herein.

Nucleobase tautomerization might induce mismatch of base pairing. Metals, involved in many important biophysical processes, have been theoretically proven to be capable of affecting tautomeric equilibria and stabilities of different nucleobase tautomers. However, direct real-space evidence on demonstrating different nucleobase tautomers and further revealing the effect of metals on their tautomerization at surfaces has not been reported to date. From the interplay of high-resolution STM imaging and DFT calculations, we show for the first time that tautomerization of guanine from G/9H to G/7H is facilitated on Au(111) by heating, whereas such tautomerization process is effectively inhibited by introducing Ni atoms due to its preferential coordination at the N7 site of G/9H. These findings may help to elucidate possible influence of metals on nucleobase tautomerization and provide from a molecular level some theoretical basis on metal-based drug design.

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The Keggin structure, known as an archetypical polyoxometalate (POM) structural motif, has widened up our fundamental understanding of the growth behavior of natural metal oxide minerals. However, devising a strategy for synthesis of such species consisting of pure-metal ions remains a great challenge. Different from those sixcoordinated early transition metal ions in Keggin POMs, lanthanide prefers higher coordination numbers, making the construction of lanthanide-Keggin structure more difficult. Here, we report the unprecedented luminescent Keggin-type Eu 13 nanocluster constructed through a facile solvothermal method using the high-symmetry macrocyclic tetrasilane (Ph 4 Si 4 O 8 ) 4− as the capping ligand. This protocol demonstrates an important proof of concept for assembly of metallasilsesquioxanes. The structure shows a rare polyoxometalate-Eu-oxo-core@SiO 2 -shell@organicshell (Eu13) consisting of a central EuO 8 cube, surrounded by 12 edge-sharing EuO 7 monocapped trigonal prisms. It is the highestnuclearity lanthanide−silsesquioxane nanocluster. Electrospray ionization mass spectrometry reveals that Eu13 is stable in solution except for some labile terminal dimethylformamide on the ligand shell, which endows Eu13 with a high catalytic activity for CO 2 cycloaddition reaction with small epoxides under ambient conditions. Eu13 also exhibits intense red luminescence upon visible light excitation (466 and 535 nm). The photophysical and photoelectric properties of the drop-casting film of Eu13 indicate its great potential in optoelectric device applications.

Laser-induced emission from the visible wavelength f-f transitions of Eu3+ is used to determine the number of distinct europium ion sites and their site symmetries in powdered monoclinic and body-centered cubic (bcc) Eu203. Identical studies are also carried out for a higher surface area catalytic bcc Eu203 material. For the monoclinic sample, the f-f emission spectrum is found to result from three distinct europium sites, all of which possess Cs symmetry. Individual emission lines are assigned to the separate emitting sites for the 5D0 -* 7Fj series for 7 = 0, 1, and 2. Emission spectra from the regular and higher surface area bcc Eu203 materials are found to originate from two distinct Eu3+ sites in the oxide lattice. The strongest emitting Eu3+ site is assigned to the known C2 symmetry site of the bcc lattice. No emission was observed from the known S6 symmetry site. The second and weaker emitting site, which is observed in the spectra of both the regular and higher surface area materials, is determined to result from an Eu3+ site with either C2 or Cj symmetry.

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The mild reaction of the preorganized silsesquioxane precursor with Mn(II) acetate under ambient conditions results in a mixed-valent {Mn II 6 Mn III 4 } nanocage (SD/Mn10) which is protected by both acyclic trimer [Si3] and cyclic tetramer [Si4]. Serendipitous capture of atmospheric CO 2 as a μ 5 -carbonate anion placed at the center supports the formation of the cluster. The magnetic analysis reveals the strong antiferromagnetic interactions between Mn ions. Moreover, the dropcasting film of SD/Mn10 shows photoelectric activity indicating its great potential as a semiconductor for photoelectric conversion applications.