Tetracycloalkenyl-meso-tetraphenylporphyrins as Models for the Effect of Non-planarity on the Light Absorption Properties of Photosynthetic Chromophores

As the size of the cycloalkenyl ring in synthetic C5-C7 tetracycloalkenyl-meso-tetraphenylporphyrins (TCnTPP) is increased the porphyrin core changes from planar to non-planar, showing that porphyrins with well-defined degrees of ruffling can be synthesized for use in systematic studies to determine the effects of non-planarity

A Solvate of the Diacetate Salt of the Octaethyltetraphenylporphyrin Dication, H\u3csub\u3e4\u3c/sub\u3eOETPP\u3csup\u3e2+\u3c/sup\u3e.2CH\u3csub\u3e3\u3c/sub\u3eCOO\u3csup\u3e-\u3c/sup\u3e.3CH\u3csub\u3e3\u3c/sub\u3eCOOH.- CH\u3csub\u3e2\u3c/sub\u3eCI\u3csub\u3e2\u3c/sub\u3e

The structure of 2,3,7,8,12,13,17,18-octaethyl-5,10,15,-20-tetraphenylporphyrin(2+) diacetate acetic acid dichloromethane solvate, C60H64N42+.2C2H3O2-.3C2H4-O2.CH2CI2, has been determined at 200K. The molecule is severely non-planar and adopts an $4 saddle shape. It is the most distorted member of the OETPP series reported to date, with displacements of the β- pyrrole C atoms from the plane of the four N atoms as great as 1.42 Å, and acute tilts of the phenyl rings relative to the porphyrin plane. The two acetate counterions act as bidentate ligands which bond to the H atoms on opposite pairs of N atoms. The crystal lattice also contains three acetic acid molecules of solvation per porphyrin molecule, all of which are involved in hydrogen bonds to the acetate molecules. An \u27innocent\u27 molecule of CH2CI2 is also present

Radiation Chemistry of Overirradiated Aqueous Solutions of Hydrogen Cyanide and Ammonium Cyanide

The radiolysis of aqueous solutions (O2-free) of HCN and NH4CN was examined at very large doses of 60Co gamma radiation (up to 230 Mrad). In this dose range the cyanide initially present (0.12 M) is decomposed and only its radiolytic products participate in the radiation-induced chemical process. It has been found that the weight of the dry residue containing the mixture of nonvolatile radiolytic products increases as doses increase up to 40 Mrad (up to about 4 g/l), but with further dose increases remains practically unchanged (NH4CN) or decreases slightly (HCN). Carboxylic and amino acids are present in overirradiated samples. At increasing doses their concentrations decrease, with the exception of oxalic and malonic acids, which are continually produced and accumulate. This is also the case with the abundant NH3 and CO2, as well as with several other products that were generated at lower radiation-chemical yields. The molecular weights of the radiolytic products are up to 20,000 daltons throughout the dose range studied. Their amounts gradually change with increasing doses above 30 Mrad: The compounds with Mw between 2,000 and 6,000 daltons become more abundant, while the amounts of polymers with Mw between 6,000 and 20,000 decrease. The relevance of these findings for studies of chemical evolution is considered

Protein-Saponin Interaction and Its Influence on Blood Lipids

Protein source and saponins have been shown to influence lipid metabolism; however, little is known regarding the chemical interactions between proteins and saponins or the impact of addition of dietary saponins to different proteins on cholesterolemia. In the present study, quillaja saponin was added to casein and to isolated soy protein (ISP) and the saponin-protein interaction was investigated by gel electrophoresis and fluoroscopy. The impact on cholesterol metabolism also was investigated in gerbils. Results from the interaction studies showed that high molecular weight complexes were formed gradually between saponins and caseins, with β-casein being most susceptible. The resulting complexes differed drastically in charge and molecular weight. In contrast, soy proteins formed insoluble aggregates during heating independently of the presence of added quillaja saponin. Data from the animal study showed that addition of saponin to ISP did not affect serum lipids, while addition of saponin to casein resulted in significant decreases of LDL cholesterol and LDL/HDL ratios, resulting in values similar to those of ISP-fed animals. These results indicate that the effect of saponins on serum lipid profiles is dependent on the source of dietary protein. This could be explained by the finding that quillaja saponin reacted differently with caseins as compared to soy protein isolate

Additions and Corrections: Nonplanar porphyrins. X-ray structures of (2,3,7,8,12,13,17,18-octaethyl- and -octamethyl-5,10,15,20-tetraphenylporphinato)zinc(II) (Journal of the American Chemical Society (1990) 112(24) (8851-8857) (10.1021/ja00180a029))

Moreover, the endotherms observed for the latter are the same, regardless of whether the bolaphile is added to a preformed MLV dispersion and incubated for 1 h at 50 °C, or whether it is initially present in the lipid mixture, prior to liposome formation. © 1990, American Chemical Society. All rights reserved

Nonplanar Porphyrins. X-ray Structures of (2,3,7,8,12,13,17,18-Octaethyl-and-Octamethyl-5,10,15,20-tetraphenylporphinato)zinc(II)

X-ray structures of the peripherally crowded porphyrins, (2,3,7,8,12,13,17,18-octaethyl-5,10,15,20-tetraphenylporphinato) Zn(II)-3MeOH solvate (ZnOETPP·3MeOH) and (2,3,7,8,12,13,17,18-octamethyl-5,10,15,20-tetraphenylporphinato) Zn(II)-pyridine-2HCCl3 (ZnOMTPP·py·2HCCl3) are reported. Both molecules are severely nonplanar and assume saddle shapes. 1H NMR data confirm that the conformational distortions are maintained in solution. The consequences of distorting the macrocycles are significant: optical, redox, basicity, and excited-state properties are altered in agreement with previous theoretical calculations. These results form part of an expanding body of structural information that clearly demonstrates that porphinoid skeletons are flexible and that distortions of the macrocycles can be imposed by steric interactions in vitro and in vivo. Conformational variations thus provide an attractively simple mechanism for modulating a wide range of physical and chemical properties of porphyrinic chromophores and prosthetic groups in vitro and in vivo. Crystallographic data. ZnN4C60H60·3CH3OH: triclinic space group P1, a = 14.017 (10) Å, b = 16.494 (7) Å, c = 13.073 (9) Å, α = 96.12 (5)°, β = 107.48 (6)°, γ = 105.23 (6)°, V = 2724.5 Å3, Z = 2; RF and RwF = 0.062, based on 4281 reflections with Fo \u3e 2σFo; T = 200 K. ZnN4C52H44·C5D5N·2HCCl3: monoclinic space group C2/c, a = 22.411 (23) Å, b = 12.552 (10) Å, c = 19.287 (12) Å, β = 98.66 (10)°, V = 5363.6 Å3, Z = 4; RF = 0.060 and RwF = 0.061, based on 1722 reflections with Fo \u3e 2σFo; T= 298 K. © 1990, American Chemical Society. All rights reserved

Effects of pre-operative isolation on postoperative pulmonary complications after elective surgery: an international prospective cohort study an international prospective cohort study

We aimed to determine the impact of pre-operative isolation on postoperative pulmonary complications after elective surgery during the global SARS-CoV-2 pandemic. We performed an international prospective cohort study including patients undergoing elective surgery in October 2020. Isolation was defined as the period before surgery during which patients did not leave their house or receive visitors from outside their household. The primary outcome was postoperative pulmonary complications, adjusted in multivariable models for measured confounders. Pre-defined sub-group analyses were performed for the primary outcome. A total of 96,454 patients from 114 countries were included and overall, 26,948 (27.9%) patients isolated before surgery. Postoperative pulmonary complications were recorded in 1947 (2.0%) patients of which 227 (11.7%) were associated with SARS-CoV-2 infection. Patients who isolated pre-operatively were older, had more respiratory comorbidities and were more commonly from areas of high SARS-CoV-2 incidence and high-income countries. Although the overall rates of postoperative pulmonary complications were similar in those that isolated and those that did not (2.1% vs 2.0%, respectively), isolation was associated with higher rates of postoperative pulmonary complications after adjustment (adjusted OR 1.20, 95%CI 1.05–1.36, p = 0.005). Sensitivity analyses revealed no further differences when patients were categorised by: pre-operative testing; use of COVID-19-free pathways; or community SARS-CoV-2 prevalence. The rate of postoperative pulmonary complications increased with periods of isolation longer than 3 days, with an OR (95%CI) at 4–7 days or ≥ 8 days of 1.25 (1.04–1.48), p = 0.015 and 1.31 (1.11–1.55), p = 0.001, respectively. Isolation before elective surgery might be associated with a small but clinically important increased risk of postoperative pulmonary complications. Longer periods of isolation showed no reduction in the risk of postoperative pulmonary complications. These findings have significant implications for global provision of elective surgical care. We aimed to determine the impact of pre-operative isolation on postoperative pulmonary complications after elective surgery during the global SARS-CoV-2 pandemic. We performed an international prospective cohort study including patients undergoing elective surgery in October 2020. Isolation was defined as the period before surgery during which patients did not leave their house or receive visitors from outside their household. The primary outcome was postoperative pulmonary complications, adjusted in multivariable models for measured confounders. Pre-defined sub-group analyses were performed for the primary outcome. A total of 96,454 patients from 114 countries were included and overall, 26,948 (27.9%) patients isolated before surgery. Postoperative pulmonary complications were recorded in 1947 (2.0%) patients of which 227 (11.7%) were associated with SARS-CoV-2 infection. Patients who isolated pre-operatively were older, had more respiratory comorbidities and were more commonly from areas of high SARS-CoV-2 incidence and high-income countries. Although the overall rates of postoperative pulmonary complications were similar in those that isolated and those that did not (2.1% vs 2.0%, respectively), isolation was associated with higher rates of postoperative pulmonary complications after adjustment (adjusted OR 1.20, 95%CI 1.05–1.36, p = 0.005). Sensitivity analyses revealed no further differences when patients were categorised by: pre-operative testing; use of COVID-19-free pathways; or community SARS-CoV-2 prevalence. The rate of postoperative pulmonary complications increased with periods of isolation longer than 3 days, with an OR (95%CI) at 4–7 days or ≥ 8 days of 1.25 (1.04–1.48), p = 0.015 and 1.31 (1.11–1.55), p = 0.001, respectively. Isolation before elective surgery might be associated with a small but clinically important increased risk of postoperative pulmonary complications. Longer periods of isolation showed no reduction in the risk of postoperative pulmonary complications. These findings have significant implications for global provision of elective surgical care