Fluorescence of Excited Complex Molecules in Mercury Photosensitization

1966 ◽  
Vol 45 (6) ◽  
pp. 2322-2323 ◽  
Author(s):  
S. Penzes ◽  
O. P. Strausz ◽  
H. E. Gunning
Keyword(s):  
Complex Molecules ◽  
Excited Complex

Maximum degree of fluorescence polarization for two-photon-excited complex molecules

1972 ◽  
Vol 17 (3) ◽  
pp. 1138-1140
Author(s):  
E. S. Voropai ◽  
I. I. Zholnerevich ◽  
A. M. Sarzhevskii
Keyword(s):  
Fluorescence Polarization ◽  
Maximum Degree ◽  
Complex Molecules ◽  
Two Photon ◽  
Excited Complex

Intramolecular vibrational energy relaxation. Decomposition of chemically activated alkylcyclobutanes

1976 ◽  
Vol 54 (6) ◽  
pp. 943-948 ◽  
Author(s):  
Fa-Mei Wang ◽  
B. S. Rabinovitch
Keyword(s):  
Relaxation Rate ◽  
Internal Energy ◽  
Vibrational Energy ◽  
Quantitative Measure ◽  
Energy Relaxation ◽  
Vibrational Energy Relaxation ◽  
Vibrationally Excited ◽  
Complex Molecules ◽  
Excited Complex ◽  
Qualitative Test

This paper describes an approach to the study of intramolecular energy relaxation of highly vibrationally excited complex molecules. The features of the decomposition of a series of chemically activated alkylcyclobutanes are outlined, including variable selectivity of the initial, non-randomized state of excitation. It is shown how this can afford both a qualitative test of the postulate of internal energy randomization employed in the Rice–Ramsperger–Kassel–Marcus treatment of unimolecular reactions, as well as a quantitative measure of the rate of relaxation. The study of the first members of this series, ethyl and dimethyl cyclobutane, is described. As expected, the first members can provide a lower limit to the relaxation rate, namely, λ > 1012 s−1.

Effect of Supercollisions on Energy Transfer in Mixtures of Bath Gases and Laser Excited Complex Molecules

1998 ◽  
Vol 31 (6) ◽  
pp. 1233-1243 ◽  
Author(s):  
G. A. Zalesskaya ◽  
D. L. Yakovlev ◽  
E. G. Sambor ◽  
D. I. Baranovsky
Keyword(s):  
Energy Transfer ◽  
Complex Molecules ◽  
Excited Complex

Alkaline Dissociation Products of Lumbricus Terrestris Hemoglobin Viewed with the STEM

1981 ◽  
Vol 39 ◽  
pp. 434-435
Author(s):  
O. H. Kapp ◽  
M. Ohtsuki ◽  
N. Robin ◽  
S. N. Vinogradov ◽  
A. V. Crewe
Keyword(s):  
Carbon Film ◽  
Lumbricus Terrestris ◽  
Uranyl Acetate ◽  
Acetate Solution ◽  
Oxygen Carriers ◽  
Complex Molecules ◽  
Thin Carbon ◽  
Thin Carbon Film ◽  
Multiple Copies ◽  
Hill Coefficients

Annelid extracellular hemoglobins are among the largest known proteins (M.W = 3.9 x 106), and together with the hemocyanins are the largest known oxygen carriers. They display oxygen affinities generally higher than those o vertebrate hemoglobins with Hill coefficients ranging from slightly higher than unity to values as high as 5-6. These complex molecules are composed of multiple copies of as many as six different polypeptides and posse: approximately 150 hemes per molecule.The samples were diluted to 100-200 μg/ml with distilled water just before application to a thin carbon film (∽15 Å thick). One percent (w/v) uranyl acetate solution was used for negative staining for 2 minutes and dried in air. The specimens were examined with the high resolution STEM. Their general appearance is that of a hexagonal bilayer (Fig. 1), each layer consisting of six spheroidal subunits. The corner to corner hexagonal dimensic is approximately 300 Å and the bilayer thickness approximately 200 Å.

Metal-, and Organocatalyst-Free One-Pot Assembly of Chiral Aza-Tricyclic Molecules: Creating Six Contiguous Stereocenters from 2-D-Structures and an Amino Acid

2020 ◽  
Author(s):  
Dung Do
Keyword(s):  
Amino Acid ◽  
Chemical Space ◽  
Structural Diversity ◽  
Therapeutic Agents ◽  
Chiral Molecules ◽  
One Pot ◽  
Complex Molecules ◽  
Chiral Catalyst ◽  
Chiral Complex ◽  
Free Process

<p>Chiral molecules with their defined 3-D structures are of paramount importance for the study of chemical biology and drug discovery. Having rich structural diversity and unique stereoisomerism, chiral molecules offer a large chemical space that can be explored for the design of new therapeutic agents.<sup>1</sup> Practically, chiral architectures are usually prepared from organometallic and organocatalytic processes where a transition metal or an organocatalyst is tailor-made for desired reactions. As a result, developing a method that enables rapid assembly of chiral complex molecules under metal- and organocatalyst-free condition represents a daunting challenge. Here we developed a straightforward route to create a chiral 3-D structure from 2-D structures and an amino acid without any chiral catalyst. The center of this research is the design of a <a>special chiral spiroimidazolidinone cyclohexadienone intermediate</a>, a merger of a chiral reactive substrate with multiple nucleophillic/electrophillic sites and a transient organocatalyst. <a>This unique substrate-catalyst (“subcatalyst”) dual role of the intermediate enhances </a><a>the coordinational proximity of the chiral substrate and catalyst</a> in the key Aza-Michael/Michael cascade resulting in a substantial steric discrimination and an excellent overall diastereoselectivity. Whereas the “subcatalyst” (hidden catalyst) is not present in the reaction’s initial components, which renders a chiral catalyst-free process, it is strategically produced to promote sequential self-catalyzed reactions. The success of this methodology will pave the way for many efficient preparations of chiral complex molecules and aid for the quest to create next generation of therapeutic agents.</p>

Visible Light-Mediated Oxidative Debenzylation

2020 ◽  
Author(s):  
Cristian Cavedon ◽  
Eric T. Sletten ◽  
Amiera Madani ◽  
Olaf Niemeyer ◽  
Peter H. Seeberger ◽  
...  
Keyword(s):  
Reaction Time ◽  
Visible Light ◽  
Functional Groups ◽  
Continuous Flow ◽  
Protecting Groups ◽  
Benzyl Ether ◽  
Complex Molecules ◽  
Protective Groups ◽  
Benzyl Ethers ◽  
Harsh Conditions

Protecting groups are key in the synthesis of complex molecules such as carbohydrates to distinguish functional groups of similar reactivity. The harsh conditions required to cleave stable benzyl ether protective groups are not compatible with many other protective and functional groups. The mild, visible light-mediated debenzylation disclosed here renders benzyl ethers orthogonal protective groups. Key to success is the use of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) as stoichiometric or catalytic photooxidant such that benzyl ethers can be cleaved in the presence of azides, alkenes, and alkynes. The reaction time for this transformation can be reduced from hours to minutes in continuous flow. <br>

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