7670-40-8Relevant academic research and scientific papers
Size-Selective Hydroformylation by a Rhodium Catalyst Confined in a Supramolecular Cage
Nurttila, Sandra S.,Brenner, Wolfgang,Mosquera, Jesús,van Vliet, Kaj M.,Nitschke, Jonathan R.,Reek, Joost N. H.
supporting information, p. 609 - 620 (2019/01/04)
Size-selective hydroformylation of terminal alkenes was attained upon embedding a rhodium bisphosphine complex in a supramolecular metal–organic cage that was formed by subcomponent self-assembly. The catalyst was bound in the cage by a ligand-template approach, in which pyridyl–zinc(II) porphyrin interactions led to high association constants (>105 m?1) for the binding of the ligands and the corresponding rhodium complex. DFT calculations confirm that the second coordination sphere forces the encapsulated active species to adopt the ee coordination geometry (i.e., both phosphine ligands in equatorial positions), in line with in situ high-pressure IR studies of the host–guest complex. The window aperture of the cage decreases slightly upon binding the catalyst. As a result, the diffusion of larger substrates into the cage is slower compared to that of smaller substrates. Consequently, the encapsulated rhodium catalyst displays substrate selectivity, converting smaller substrates faster to the corresponding aldehydes. This selectivity bears a resemblance to an effect observed in nature, where enzymes are able to discriminate between substrates based on shape and size by embedding the active site deep inside the hydrophobic pocket of a bulky protein structure.
Synthesis and properties of mesobilirubins XIIγ and XIIIγ and their mesobiliverdins
Sabido, Portia Mahal G.,Lightner, David A.
, p. 775 - 789 (2014/05/20)
The title pigments, with propionic acid groups displaced to the lactam end rings, were synthesized for the first time by the "1 + 2 + 1" approach, coupling two equivalents of a monopyrrole to a dipyrrylmethane (to give XIIγ), or the "2 + 2" approach, self-coupling two equivalents of a dipyrrinone (to give XIIIγ). Using the "1 + 2 + 1" approach, mesobilirubin IIIα was also prepared. Mesobilirubins XIIγ and XIIIγ are more polar than mesobilirubin IIIα and unlike IIIα cannot effectively engage the propionic acid groups in intramolecular hydrogen bonding to the dipyrrinone components. The new mesobilirubins give exciton coupled circular dichroism spectra in the presence of human serum albumin or quinine, with the XIIγ isomer exhibiting Cotton effect intensities nearly as strong as those from the IIIα isomer; whereas, the XIIIγ isomer exhibits far weaker intensities. Mesobilirubin IIIα requires glucuronidation for hepatobiliary elimination; whereas, XIIγ and XIIIγ do not, and they are excreted intact across the liver into bile. The corresponding biliverdins XIIγ and XIIIγ are reduced only slowly by biliverdin IXα reductase, in contrast to the fast reduction of the natural IXα isomer. Graphical abstract: [Figure not available: see fulltext.]
Fluorinated photosensitizers: Synthesis, photophysical, electrochemical, intracellular localization, in vitro photosensitizing efficacy and determination of tumor-uptake by 19F in vivo NMR spectroscopy
Pandey, Suresh K.,Gryshuk, Amy L.,Graham, Andrew,Ohkubo, Kei,Fukuzumi, Shunichi,Dobhal, Mahabeer P.,Zheng, Gang,Ou, Zhongping,Zhan, Riqiang,Kadish, Karl M.,Oseroff, Allan,Ramaprasad,Pandey, Ravindra K.
, p. 10059 - 10073 (2007/10/03)
For in vivo NMR studies, starting from pyrroles, a series of fluorinated porphyrins were synthesized by following the MacDonald reaction conditions. Upon reaction with osmium tetroxide, a fluorinated porphyrin containing four trifluoromethyl groups (12 fl
SYNTHESIS OF RIGIDLY LINKED TRIAD MOLECULES BASED ON OCTAALKYLPORPHYRIN, CAPABLE OF MULTISTEP ELECTRON TRANSFER
Gribkov, A.A.,Borovkov, V.V.,Evstigneeva, R.P.,Sakata, Y.
, p. 905 - 915 (2007/10/02)
We have designed and carried out the synthesis of triad model systems containing octaalkylporphyrin, benzoquinone, and trichlorobenzoquinone with an oxidation-reduction potential gradient in the molecule.The quinone moieties are fixed relative to the porphyrin using spirononane and methylene spacers.
Electron transfer in bis-porphyrin donor-acceptor compounds with polyphenylene spacers shows a weak distance dependence
Helms, Anna,Heiler, David,McLendon, George
, p. 6227 - 6238 (2007/10/02)
A series of phenylene-bridged bis-porphyrin adducts have been synthesized, containing one, two, or three phenyl bridges. Complete synthetic details are provided. For studies of photochemical electron transfer, mixed metals wre incorporated, with zinc in one porphyrin macrocycle and FeIII (bis-imidazole) in the other macrocycle. When photoexcited, an electron is transferred from Zn to FeIII. The rate of this process drops only slowly with distance: kα exp(βr), with β = 0.4 A?-1. This dependence can be predicted by a simple theory which assumes that the drop does not reflect increased distance, but rather reflects the break in conjugation which occurs at each phenyl juncture due to the biphenyl twist angle of ca. 50°. Inefficient overlap in this angle results in a rate drop of ca. 6-fold per phenyl ring, in good agreement with the observed results.
Conjugated Macrocycles Related to the Porphyrins. Part 2. Further Synthetic and Spectroscopic Studies on Difuryl Analogs of the Oxophlorins
Lash, Timothy D.,Armiger, Yoek Lin See-Tow
, p. 965 - 970 (2007/10/02)
The synthesis of three difuryl analogs of the oxophlorins is described.In common with the tetrapyrrolic oxophlorins, these compounds favor the keto tautomers and little, if any, of the enol tautomers are present in neutral solutions.Unlike the tetrapyrrol
Synthetic and Biosynthetic Studies of Porphyrins. Part 9. Synthesis of Isocoproporphyrin, Dehydroisocoproporphyrin, and De-ethylisocopropophyrin
Jackson, Anthony H.,Lash, Timothy D.,Ryder, David J.
, p. 287 - 298 (2007/10/02)
The title compounds, which were extracted by patients suffering from porphyria cutanea tarda or rats poisoned with hexachlorobenzene have been synthesized by the b-oxobilane route.Isocoproporphyrin tetramethyl ester (7a) were prepared from pyrromethanes c
Reactions on solid supports part II: a convenient method for synthesis of pyrromethanes using a montmorillonite clay as catalyst
Jackson, Anthony H.,Pandey, Ravindra K.,Nagaraja Rao,Roberts, Edward
, p. 793 - 796 (2007/10/02)
α-Acetoxymethylpyrroles couple with α-free pyrroles in presence of Montmorillonite clay to form unsymmetrical pyrromethanes in excellent yields. Symmetrical pyrromethanes were also prepared in a similar manner by clay catalysed self-condensation of α-acet
