The synthesis and chiral resolution of free-base and Ni(II) complexes of a number of derivatives of meso-tetraphenylmorpholinochlorins, with and without direct β-carbon-to-o-phenyl linkages to the flanking phenyl groups, is described. The morpholinochlorins, a class of stable chlorin analogues, were synthesized in two to three steps from meso-tetraphenylporphyrin. The conformations and the relative stereostructures of a variety of free-base and Ni(II) complexes of these morpholinochlorins were elucidated by X-ray diffractometry. Steric and stereoelectronic arguments explain the relative stereoarray of the morpholino-substituents, which differ in the free-base and Ni(II) complexes, and in the monoalkoxy, β-carbon-to-o-phenyl linked morpholinochlorins, and the dialkoxy derivatives. The Ni(II) complexes were all found to be severely ruffled whereas the free-base chromophores are more planar. As a result of the helimeric distortion of their porphyrinoid chromophores, the ruffled macrocycles possess a stable inherent element of chirality. Most significantly, resolution of the racemic mixtures was achieved, both by classical methods via diastereomers and by HPLC on a chiral phase. Full CD spectra were recorded and modeled using quantum-chemical computational methods, permitting, for the first time, an assignment of the absolute configurations of the chromophores. The report expands the range of known pyrrole-modified porphyrins. Beyond this, it introduces large chiral porphyrinoid π-systems that exist in the form of two enantiomeric, stereochemically stable helimers that can be resolved. This forms the basis for possible future applications, for example, in molecular-recognition systems or in materials with chiroptic properties.
Objectives:DiabCare India 2011 was a cross-sectional study in patients with diabetes mellitus, undertaken to investigate the relationship between diabetes control, management and complications in a subset of urban Indian diabetes patients treated at referral diabetes care centres in India.Materials and Methods:This was a cross-sectional, multicentre (330 centres) survey in 6168 diabetes patients treated at general hospitals, diabetes clinics and referral clinics across India. Patient data, including medical and clinical examination reports during the past year were collected during their routine visit. The patients’ and physicians’ perceptions about diabetes management were recorded using a questionnaire.Results:A total of 6168 subjects with diabetes (95.8% type 2), mean age 51.9 ± 12.4 years and mean duration of diabetes, 6.9 ± 6.4 years were included. Mean HbA1c was 8.9 ± 2.1% and the mean fasting (FPG), post prandial (PPG) and random (RBG) plasma glucose levels were 148 ± 50 mg/dl 205 ± 66 mg/dl and 193 ± 68mg/dl respectively. Neuropathy was the most common complication (41.4%); other complications were: Foot (32.7%), eye (19.7%), cardiovascular (6.8%) and nephropathy (6.2%). The number of diabetic complications increased with mean duration of diabetes. Most (93.2%) of the patients were on oral anti-diabetic drugs (OADs) and 35.2% were on insulin (±OADs). More than 15% physicians felt that the greatest barrier to insulin therapy from patient's perspective were pain and fear of using injectable modality; 5.2% felt that the greatest barrier to insulin therapy from physician's perspective was the treatment cost; 4.8% felt that the major barriers to achieve optimum diabetic care in practice was loss to follow-up followed by lack of counselling (3.9%) and treatment compliance (3.6%).Conclusion:DiabCare India 2011 has shown that type 2 diabetes sets in early in Indians and glycaemic control is often sub-optimal in these patients. These results indicate a need for more structured intervention at an early stage of the disease and need for increased awareness on benefits of good glycaemic control. It cannot be overemphasized that the status of diabetes care in India needs to be further improved. (ClinTrials.gov identifier: NCT01351922)
The OsO(4)-mediated dihydroxylation of meso-tetraphenylporphyrin N-oxide yields two regioisomeric chlorin N-oxides. These chlorin N-oxides can be manipulated to provide pairs of regioisomers of pyrrole-modified porphyrin N-oxides. The UV-vis absorption and fluorescence emission spectra of the neutral and protonated regioisomers are distinct from each other, and generally different from the parent chromophore. The outcome of diol oxidation reactions of some N-oxide diolchlorins varies from the corresponding reactions of the parent diolchlorins. The crystal structure of a free base porpholactone N-oxide carrying the N-oxide on the oxazolone moiety is reported.
We have synthesized a small library of blue‐to‐green emissive single benzene‐based fluorophores (SBFs) in a short synthetic sequence. The molecules exhibit good Stokes shift in the range of 60–110 nm and select examples also possess very high fluorescence quantum yields of up to 87%. Theoretical investigations into the ground state and excited state geometries of many of these compounds reveal that good degree of planarization between the electron donor secondary amines and electron accepting benzodinitrile units can be achieved under certain solvatochromic conditions, giving rise to the strongly fluorescent behavior. On the other hand, the excited state geometry which lacks co‐planarity of the donor amine and the single benzene moiety can open up a non‐fluorescent channel. Additionally, in molecules with a dinitrobenzene acceptor, the perpendicular nitro moieties render the molecules completely non‐emissive.
The methyltrioxorhenium (MTO)/pyrazole-mediated H(2)O(2) oxidation of octaethylporphyrin and a number of meso-tetraarylporphyrins offers simple and good yielding access to the corresponding N-oxides, only few of which were prepared before. The crystal structure of a free base tetraarylporphyrin N-oxide demonstrates the degree to which the oxygenated pyrrole moiety is slanted with respect to the rest of the otherwise nearly planar macrocycle. The method is also suitable to the preparation of hitherto unknown chlorin N-oxides. Oxidation of meso-tetraphenyldithiaporphyrin and meso-tetraphenyldithiachlorin furnishes the corresponding novel S-oxides. The optical properties of the novel chromophores are described and rationalized.
trans-Diolchlorin was prepared by nucleophilic addition of methyl-Grignard bromide to meso-tetraphenyl-2,3-dioxoporphyrin, as its free base or Ni(II) complex. The trans-configuration of the vic-diol functionality was shown by single crystal X-ray diffractometry. The nickel complex of the trans-dimethyldiol proved susceptible to Pb(IV) acetate-induced, oxidative diol cleavage, generating a meso-tetraphenylsecochlorin bismethylketone Ni(II) complex, the first example of this chromophore class. Under Brønsted-basic conditions, this bisketone cyclized via an intramolecular aldol condensation to provide a meso-tetraphenyloxypyriporphyrin. Reduction of this porphyrin analog saturated the double bond in the pyridinone moiety, generating an oxypyrichlorin. Reaction of the meso-tetraphenylsecochlorin bismethylketone Ni(II) complex with Lawesson's reagent induced the formation of a thiomorpholinochlorin substituted with two methylene groups, the first example of any porphyrin analog containing a thiomorpholine moiety.
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