A novel sulfonated CNN pincer ligand has been designed to support CH and O2 activation at a Pt­(II) center. The derived cycloplatinated aqua complex 7 was found to be one of the most active reported homogeneous Pt catalysts for H/D exchange between studied arenes (benzene, benzene-d 6, toluene-d 8, p-xylene, and mesitylene) and 2,2,2-trifluoroethanol (TFE) or 2,2,2-trifluoroethanol-d; the TON for C6D6 as a substrate is >250 after 48 h at 80 °C. The reaction is very selective; no benzylic CH bond activation was observed. The per-CH-bond reactivity diminishes in the series benzene (19) > toluene (p-CH:m-CH:o-CH = 1:0.9:0.2) > xylene (2.9) > mesitylene (1.1). The complex 7 reacts slowly in TFE solutions under ambient light but not in the dark with O2 to selectively produce a Pt­(IV) trifluoroethoxo derivative. The H/D exchange reaction kinetics and results of the DFT study suggest that complex 7, and not its TFE derivatives, is the major species responsible for the arene CH bond activation. The reaction deuterium kinetic isotope effect, k H/k D = 1.7, the reaction selectivity, and reaction kinetics modeling suggest that the CH bond cleavage step is rate-determining.

1. The effects of intragastric glucose feeding and L-tri-iodothyronine (T3) administration on rates of hepatic and brown-fat lipogenesis in vivo were examined in fed and 48 h-starved rats. 2. T3 treatment increased hepatic lipogenesis in the fed but not the starved animals. Brown-fat lipogenesis was unaffected or slightly decreased by T3 treatment of fed or starved rats. 3. Intragastric glucose feeding increased hepatic lipogenesis in control or T3-treated fed rats, but did not increase hepatic lipogenesis in starved control rats. Glucose feeding increased hepatic lipogenesis if the starved rats were treated with T3. Glucose feeding increased rates of brown-fat lipogenesis in all experimental groups. The effects of glucose feeding on liver and brown-fat lipogenesis were mimicked by insulin injection. 4. The increase in hepatic lipogenesis in T3-treated 48 h-starved rats after intragastric glucose feeding was prevented by short-term insulin deficiency, but not by (-)-hydroxycitrate, an inhibitor of ATP citrate lyase. The increase in lipogenesis in brown adipose tissue in response to glucose feeding was inhibited by both short-term insulin deficiency and (-)-hydroxycitrate. 5. The results tend to preclude pyruvate kinase and acetyl-CoA carboxylase as the sites of interaction of insulin and T3 in the regulation of hepatic lipogenesis in 48 h-starved rats. Other potential sites of interaction are discussed.

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Glucose or insulin increased lipogenesis (measured in vivo using 3H2O) in brown fat of starved rats. Such increases were associated with activation of pyruvate dehydrogenase and increased use of glucose as a lipogenic precursor (monitored as an increase in the 14C/3H ratio in brown-fat fatty acids in rats injected with both 3H20 and [U-14C]glucose). (-) Hydroxycitrate did not inhibit basal rates of brown-fat lipogenesis in starved rats but suppressed the increases in lipogenesis and glucose utilization observed in response to insulin. (-)Hydroxycitrate did not, however, inhabit the increase in 14C/3H observed after insulin treatment. The results indicate that in brown fat, glucose is utilized for fatty-acid synthesis predominantly via citrate, and that insulin acts to increase lipogenesis at site(s) prior to citrate cleavage. As basal rates of lipogenesis were not inhibited by (-)hydroxycitrate, it is suggested that acetate may be a lipogenic substrate for brown fat in starvation, and experiments are described which support this suggestion.

The synthesis, characterization, and structures of a series of homoleptic and heteroleptic copper(I) complexes supported by N-heterocyclic chalcogenone ligands is reported herein. The quasi-reversible Cu(II/I) reduction potentials of these copper complexes with monodentate (dmit or dmise) and/or bidentate (Bmm(Me), Bsem(Me), Bme(Me), Bsee(Me)) chalcogenone ligands are highly dependent upon the nature and number of the donor groups and can be tuned over a 470 mV range (-369 to 102 mV). Copper-selone complexes have more negative Cu(II/I) reduction potentials relative to their thione analogs by an average of 137 mV, and increasing the number of methylene units linking the heterocyclic rings in the bidentate ligands results in more negative reduction potentials for their copper complexes. This ability to tune the copper reduction potentials over a wide range has potential applications in synthetic and industrial catalysis as well as the understanding of important biological processes such as electron transfer in blue copper proteins and respiration.

Two novel sulfonated CNN‐pincer ligands 1b and 1c and the corresponding chloro and aqua complexes K[CNNLPtCl] and CNNLPt(H2O), 3b–3c and 2b–2c, were prepared and fully characterized including single crystal X‐ray diffraction. Along with the previously described complexes 2a and 3a, the derivatives of a CNN pincer ligand 1a, these complexes form a family of structurally similar compounds where the pincer core rigidity increases in the series 2a (3a)<2b (3b)<2c (3c), as deduced from their XRD data. The increased ligand rigidity affects the aqua ligand dissociation energy of the CNNLPt(H2O) complexes, as it follows from DFT calculations and as is reflected in the increased reactivity of the aqua complexes 2a, 2b and 2c in processes that involve aqua ligand loss. Among these processes the formation of the presumed dinuclear complexes CNNL2Pt2 and, importantly, catalytic C−D bond cleavage in C6D6 were studied in 2,2,2‐trifluoroethanol solutions. The C−D bond cleavage reactivity was quantified as the rate of H/D exchange between C6D6 and CF3CH2OH at 80 °C.

We report platinum catalysts for the efficient aerobic oxidation of olefins to form epoxides and/or derived glycol monoethers. The catalystsdiaqua and dichloro Pt II complexes supported by the ligand di(2-pyridine)methanesulfonate (dpms)are most active when they are covalently tethered to mesoporous silica nanoparticles (MSNs). Supporting the molecular Pt complexes on the MSNs prevents bimolecular catalyst deactivation. Using this strategy, >40 000 turnovers are achieved for the aerobic oxidation of norbornene in 2,2,2-trifluoroethanol. The position of the tether and the nature of other ligands in the metal coordination sphere (aqua, hydroxo, or chloro) are shown to affect the catalyst activity. The new MSN-supported Pt materials were characterized by nuclear magnetic resonance (NMR) spectroscopy, nitrogen physisorption, powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and thermogravimetric analysis (TGA).

The effects of intragastric feeding with glucose and of the administration of L-triiodothyronine (T3) on in vivo rates of hepatic lipogenesis were investigated in control (fed ad libitum on normal diet), diabetic (fed ad libitum on normal diet), fat-fed (fed ad libitum on high-fat diet), and starved (food removed for 48 h) rats. Two days of T3 treatment increased hepatic lipogenesis in control and fat-fed animals but not in the diabetic or starved animals, although increases in lipogenesis in diabetic animals were observed after 4 days of T3 treatment. Intragastric glucose feeding increased hepatic lipogenesis in the livers of control animals and T3-treated control animals. Such increases are mediated by an increase in the circulating insulin concentration, as increases are not observed in diabetic rats or T3-treated diabetic rats. Glucose feeding failed to increase hepatic lipogenesis in fat-fed rats or starved rats. Insulin injection together with glucose feeding increased lipogenesis in the fat-fed group but not the starved group; i.e., impaired insulin secretion following an oral glucose load may in part explain the lack of response in the fat-fed but not the starved animals. Marked increases in hepatic lipogenesis after glucose feeding were, however, observed if either the starved or the fat-fed animals were treated with T3. The physiological implications of these observations are discussed.