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Transition metal tetrylene complexes offer great opportunities for molecular cooperation due to the ambiphilic character of the group 14 element. Here we focus on the coordination of germylene [(ArMes2)2Ge :] (ArMes=C6H3‐2,6‐(C6H2‐2,4,6‐Me3)2) to [RhCl(COD)]2 (COD=1,5‐cyclooctadiene), which yields a neutral germyl complex in which the rhodium center exhibits both η6‐ and η2‐coordination to two mesityl rings in an unusual pincer‐type structure. Chloride abstraction from this species triggers a singular dehydrogenative double C−H bond activation across the Ge/Rh motif. We have isolated and fully characterized three rhodium‐germyl species associated to three C−H cleavage events along this process. The reaction mechanism has been further investigated by computational means, supporting the key cooperative action of rhodium and germanium centers. [ABSTRACT FROM AUTHOR]

Heavier group 14 element cations exhibit a remarkable reactivity that has typically hampered their isolation. For the few available examples, the role of π‐arene interactions is crucial to provide kinetic stabilization, but dynamic and structural information on those contacts is yet limited. In this study we have accessed the metalogermylenium cation [(PMe2ArDipp2)AuGe(ArDipp2)Cl]+ (4+) (ArDipp2=C6H3‐2,6‐(C6H3‐2,6‐iPr2)2) that has been structurally characterized with three different non‐coordinating counter anions. These studies provide for the first time dynamic information about the conformational rearrangement that characterizes π‐arene bonding thorough a series of X‐ray diffraction structural snapshots. Computational studies reveal the weak character of the π‐arene bonding (ca. 2 kcal mol−1) that can be described as the donation from a πC=C bond toward the empty p valence orbital of germanium. [ABSTRACT FROM AUTHOR]

Six strongly fluorescent four-coordinate organoboron N,C chelates containing an aryl isoquinoline skeleton were prepared. Remarkably, the fluorescence quantum yields reach values of up to 0.74 in oxygen-free toluene. The strong BN interaction was corroborated by the single-crystal X-ray analysis of two dyes. The intramolecular charge-transfer character of the fluorophores was evidenced by solvatochromism studies and time-dependent DFT calculations at the PCM(toluene)/CAM-B3LYP/6-311++G(2d,p)//PCM(toluene)/B3LYP/6-311G(2d,p) level of theory. The compounds combine high chemical stability with high photostability, especially when equipped with electron-donating substituents. The strong fluorescence and the large Stokes shifts predestine these compounds for use in confocal fluorescence microscopy. This was demonstrated for the imaging of the N13 mouse microglial cell line. Moreover, significant two-photon absorption cross sections (up to 61 GM) allow the use of excitation wavelengths in the near-infrared region (>800 nm). [ABSTRACT FROM AUTHOR]

The present study provides a deeper view of protein functionality as a function of temperature, salt and pressure in deep-sea habitats. A set of eight different enzymes from five distinct deep-sea (3040-4908 m depth), moderately warm (14.0-16.5°C) biotopes, characterized by a wide range of salinities (39-348 practical salinity units), were investigated for this purpose. An enzyme from a 'superficial' marine hydrothermal habitat (65°C) was isolated and characterized for comparative purposes. We report here the first experimental evidence suggesting that in saltsaturated deep-sea habitats, the adaptation to high pressure is linked to high thermal resistance (P value = 0.0036). Salinity might therefore increase the temperature window for enzyme activity, and possibly microbial growth, in deep-sea habitats. As an example, Lake Medee, the largest hypersaline deepsea anoxic lake of the Eastern Mediterranean Sea, where the water temperature is never higher than 16°C, was shown to contain halopiezophilic-like enzymes that are most active at 70°C and with denaturing temperatures of 71.4°C. The determination of the crystal structures of five proteins revealed unknown molecular mechanisms involved in protein adaptation to poly-extremes as well as distinct active site architectures and substrate preferences relative to other structurally characterized enzymes. [ABSTRACT FROM AUTHOR]

Metal‐only Lewis pairs (MOLPs) in which the two metal fragments are solely connected by a dative M→M bond represent privileged architectures to acquire fundamental understanding of bimetallic bonding. This has important implications in many catalytic processes or supramolecular systems that rely on synergistic effects between two metals. However, a systematic experimental/computational approach on a well‐defined class of compounds is lacking. Here we report a family of MOLPs constructed around the RhI precursor [(η5‐C5Me5)Rh(PMe3)2] (1) with a series of s, p and d‐block metals, mostly from the main group elements, and investigate their bonding by computational means. Among the new MOLPs, we have structurally characterized those formed by dative bonding between 1 and MgMeBr, AlMe3, GeCl2, SnCl2, ZnMe2 and Zn(C6F5)2, as well as spectroscopically identified the ones resulting from coordination to MBArF (M=Na, Li; BArF−=[B(C6H2‐3,5‐(CF3)2)4]−) and CuCl. Some of these compounds represent unique examples of bimetallic structures, such as the first unambiguous cases of Rh→Mg dative bonding or base‐free rhodium bound germylene and stannylene species. Multinuclear NMR spectroscopy, including 103Rh NMR, is used to probe the formation of Rh→M bonds. A comprehensive theoretical analysis of those provides clear trends. As anticipated, greater bond covalency is found for the more electronegative acids, whereas ionic character dominates for the least electronegative nuclei, though some degree of electron sharing is identified in all cases. [ABSTRACT FROM AUTHOR]

Energy transfer cassettes that build on the platform of boronic acid derived salicylidenehydrazone (BASHY) complexes were prepared. The functional flexibility of the BASHY chromophore was underpinned by its tunable role as energy donor or acceptor, integrated in compact and non‐conjugated bichromophoric dyads. The energy transfer is highly efficient (ΦET>0.95) and is assumed to proceed mainly via a through‐bond mechanism. Both constituent chromophores benefit mutually from their integration in the cassettes: a) The pseudo Stokes shift is increased to 110–200 nm; b) the antenna (donor) chromophore improves the light absorption of the acceptor chromophore; and c) the emission window of the BASHY chromophore is expanded in the BASHY‐Bodipy dye without using strategies that compromise the observation of high quantum yields. The application of the cassettes for the formulation of fluorescent polymeric nanoparticles, that can be internalized in cells and observed by fluorescence imaging, was demonstrated using the BASHY‐Bodipy dye as an example. Stronger together: The boronic acid derived salicylidenehydrazone (BASHY) dye platform has been integrated in energy transfer cassettes, showing high photophysical flexibility. Brightly fluorescent dyes where obtained that can be formulated with polymeric organic nanoparticles with application potential in bioimaging. [ABSTRACT FROM AUTHOR]

Euryarchaea from the genus H alorhabdus have been found in hypersaline habitats worldwide, yet are represented by only two isolates: H alorhabdus utahensis AX-2T from the shallow Great Salt Lake of Utah, and H alorhabdus tiamatea SARL4 BT from the Shaban deep-sea hypersaline anoxic lake ( DHAL) in the Red Sea. We sequenced the H . tiamatea genome to elucidate its niche adaptations. Among sequenced archaea, H . tiamatea features the highest number of glycoside hydrolases, the majority of which were expressed in proteome experiments. Annotations and glycosidase activity measurements suggested an adaptation towards recalcitrant algal and plant-derived hemicelluloses. Glycosidase activities were higher at 2% than at 0% or 5% oxygen, supporting a preference for low-oxygen conditions. Likewise, proteomics indicated quinone-mediated electron transport at 2% oxygen, but a notable stress response at 5% oxygen. H alorhabdus tiamatea furthermore encodes proteins characteristic for thermophiles and light-dependent enzymes (e.g. bacteriorhodopsin), suggesting that H . tiamatea evolution was mostly not governed by a cold, dark, anoxic deep-sea habitat. Using enrichment and metagenomics, we could demonstrate presence of similar glycoside hydrolase-rich H alorhabdus members in the Mediterranean DHAL Medee, which supports that H alorhabdus species can occupy a distinct niche as polysaccharide degraders in hypersaline environments. [ABSTRACT FROM AUTHOR]