Size-Dependent Interaction of the Poly(<i>N</i>-vinyl-2-pyrrolidone) Capping Ligand with Pd Nanocrystals

Pd nanocrystals were prepared by the reduction of a H₂PdCl₄ aqueous solution with C₂H₄ in the presence of different amounts of poly­(<i>N</i>-vinyl-2-pyrrolidone) (PVP). Their average size decreases monotonically as the PVP monomer/Pd molar ratio increases up to 1.0 and then does not vary much at higher PVP monomer/Pd molar ratios. Infrared spectroscopy and X-ray photoelectron spectroscopy results reveal the interesting size-dependent interaction of PVP molecules with Pd nanocrystals. For fine Pd nanocrystals capped with a large number of PVP molecules, each PVP molecule chemisorbs with its oxygen atom in the ring; for large Pd nanocrystals capped by a small number of PVP molecules, each PVP molecule chemisorbs with both the oxygen atom and nitrogen atom in the ring, which obviously affects the structure of chemisorbed PVP molecules and even results in the breaking of involved C–N bonds of some chemisorbed PVP molecules. Charge transfer always occurs from a chemisorbed PVP ligand to Pd nanocrystals. These results provide novel insights into the PVP–metal nanocrystal interaction, which are of great importance in the fundamental understanding of surface-mediated properties of PVP-capped metal nanocrystals

Oxygen Vacancy-Induced Novel Low-Temperature Water Splitting Reactions on FeO(111) Monolayer-Thick Film

We have used XPS, UPS, and TDS to comparatively study water chemisorption and reaction on stoichiometric FeO(111) monolayer-thick film on Pt(111), stoichiometric FeO(111) monolayer-thick islands on Pt(111), and FeO(111) monolayer-thick films with oxygen vacancies on Pt(111) at 110 K. On stoichiometric FeO(111) monolayer-thick film, water undergoes reversible molecular adsorption. On stoichiometric FeO(111) monolayer-thick islands on Pt(111), water dissociates at coordination-unsaturated Fe­(II) sites of the FeO(111)–Pt­(111) interface to form OH following H₂O + Fe_CUS + FeO → Fe_CUS–O_wH + FeOH in which O_w means O from H₂O. Upon heating, H₂ evolution occurs above 500 K. On FeO(111) monolayer-thick films with oxygen vacancies, water dissociates and molecularly chemisorbs to form a mixed adsorbate layer of H­(a), OH, and H₂O­(a) following both H₂O + Fe–O_vacancy + FeO → FeO_wH + FeOH and H₂O + 2 Fe–O_vacancy → FeO_wH + H­(a)–Fe–O_vacancy. Upon heating, besides the high-temperature H₂ evolution, additional H₂ desorption peaks appear simultaneously with the low-temperature desorption features of adsorbed H₂O­(a), revealing novel low-temperature water splitting reactions. The formation of hydrated-proton surface species within a mixed adsorbate layer of H­(a), OH, and H₂O­(a) on FeO(111) monolayer-thick films with oxygen vacancies is proposed to explain such novel low-temperature water splitting reactions. These results greatly enrich the surface chemistry of water on solid surfaces

A Convenient Strategy for Designing a Soft Nanospace: An Atomic Exchange in a Ligand with Isostructural Frameworks

Direct observation of gas molecules confined in the nanospace of porous materials by single-crystal X-ray diffraction (SXRD) technique is significant because it leads to deep insight into the adsorption mechanism and the actual state of the adsorbents in molecular level. A recent study revealed that flexibility is one of the important factors to achieve periodic guest accommodation in the nanospace enabling direct observation of gas molecules. Here, we report a convenient strategy to tune the framework flexibility by just an atomic exchange in a ligand, which enables us to easily construct a soft nanospace as the best platform to study gas adsorption. Indeed, we succeeded to observe C₂H₂ and CO₂ molecules confined in the pores of a flexible porous coordination polymer (<b>PCP-N</b>) in different configurations using SXRD measurement, whereas gas molecules in a rigid framework (<b>PCP-C</b>) isostructural to <b>PCP-N</b> were not seen crystallographically. The result of the coincident in situ powder X-ray diffraction and adsorption measurement for <b>PCP-N</b> unambiguously showed that the framework could flexibly transform to trap gas molecules with a commensurate fashion. In addition, for <b>PCP-N</b>, we found that the adsorbed gas molecules induced significant structural change involving dimensional change of the pore from one-dimensional to three-dimensional, and subsequently, additional gas molecules formed periodic molecular clusters in the nanospace

A Convenient Strategy for Designing a Soft Nanospace: An Atomic Exchange in a Ligand with Isostructural Frameworks

Direct observation of gas molecules confined in the nanospace of porous materials by single-crystal X-ray diffraction (SXRD) technique is significant because it leads to deep insight into the adsorption mechanism and the actual state of the adsorbents in molecular level. A recent study revealed that flexibility is one of the important factors to achieve periodic guest accommodation in the nanospace enabling direct observation of gas molecules. Here, we report a convenient strategy to tune the framework flexibility by just an atomic exchange in a ligand, which enables us to easily construct a soft nanospace as the best platform to study gas adsorption. Indeed, we succeeded to observe C₂H₂ and CO₂ molecules confined in the pores of a flexible porous coordination polymer (<b>PCP-N</b>) in different configurations using SXRD measurement, whereas gas molecules in a rigid framework (<b>PCP-C</b>) isostructural to <b>PCP-N</b> were not seen crystallographically. The result of the coincident in situ powder X-ray diffraction and adsorption measurement for <b>PCP-N</b> unambiguously showed that the framework could flexibly transform to trap gas molecules with a commensurate fashion. In addition, for <b>PCP-N</b>, we found that the adsorbed gas molecules induced significant structural change involving dimensional change of the pore from one-dimensional to three-dimensional, and subsequently, additional gas molecules formed periodic molecular clusters in the nanospace

Final multivariate model predicting blood pressure control in hypertensive patients with CHD.

<p>CHD: coronary heart disease; BMI: body mass index; CCB: calcium channel blockers; OR: odds ratios; 95% CIs: 95% confidential intervals.</p

Bivariate analysis of factors affecting blood pressure control in hypertensive patients with CHD.

<p>CHD: coronary heart disease; BMI: body mass index; MI: myocardial infarction; CCB: calcium channel blockers; ACEI: angiotension converting enzyme inhibitor; ARB: angiotension receptor blocker.</p

Medication use among hypertensive patients with CHD (N = 3279).

<p>CHD: coronary heart disease; CCB: calcium channel blockers; ACEI: angiotension converting enzyme inhibitor; ARB: angiotension receptor blocker.</p

Antihypertensive therapy rate and prevalence of blood pressure control.

<p>Antihypertensive therapy rate and prevalence of blood pressure control.</p

Demographic and clinical characteristics hypertensive patients with CHD, CCEP 2006 (N = 3279).

<p>CCEP: China Cholesterol Education Program; BMI: body mass index; MI: myocardial infarction; CHD: coronary heart disease; SBP: systolic blood pressure; DBP: diastolic blood pressure; TC: cholesterol; TG: triglyceride; HDL-C: high-density lipoprotein cholesterol; LDL-C: low-density lipoprotein cholesterol; FPG: fasting plasma glucose.</p

Odds ratios and 95% confidence intervals predicting blood pressure control attainment by type of antihypertensive medication use.

<p>Odds ratios and 95% confidence intervals predicting blood pressure control attainment by type of antihypertensive medication use.</p