1732-23-6Relevant academic research and scientific papers
Pyrene Molecular Orbital Shuffle—Controlling Excited State and Redox Properties by Changing the Nature of the Frontier Orbitals
Merz, Julia,Fink, Julian,Friedrich, Alexandra,Krummenacher, Ivo,Al Mamari, Hamad H.,Lorenzen, Sabine,Haehnel, Martin,Eichhorn, Antonius,Moos, Michael,Holzapfel, Marco,Braunschweig, Holger,Lambert, Christoph,Steffen, Andreas,Ji, Lei,Marder, Todd B.
, p. 13164 - 13180 (2017)
We show that by judicious choice of substituents at the 2- and 7-positions of pyrene, the frontier orbital order of pyrene can be modified, giving enhanced control over the nature and properties of the photoexcited states and the redox potentials. Specifically, we introduced a julolidine-like moiety and Bmes2 (mes=2,4,6-Me3C6H2) as very strong donor (D) and acceptor (A), respectively, giving 2,7-D-π-D- and unsymmetric 2,7-D-π-A-pyrene derivatives, in which the donor destabilizes the HOMO?1 and the acceptor stabilizes the LUMO+1 of the pyrene core. Consequently, for 2,7-substituted pyrene derivatives, unusual properties are obtained. For example, very large bathochromic shifts were observed for all of our compounds, and unprecedented green light emission occurs for the D/D system. In addition, very high radiative rate constants in solution and in the solid state were recorded for the D-π-D- and D-π-A-substituted compounds. All compounds show reversible one-electron oxidations, and Jul2Pyr exhibits a second oxidation, with the largest potential splitting (ΔE=440 mV) thus far reported for 2,7-substituted pyrenes. Spectroelectrochemical measurements confirm an unexpectedly strong coupling between the 2,7-substituents in our pyrene derivatives.
Unlocking Amides through Selective C–N Bond Cleavage: Allyl Bromide-Mediated Divergent Synthesis of Nitrogen-Containing Functional Groups
Govindan, Karthick,Chen, Nian-Qi,Chuang, Yu-Wei,Lin, Wei-Yu
supporting information, p. 9419 - 9424 (2021/11/30)
We report a new set of reactions based on the unlocking of amides through simple treatment with allyl bromide, creating a common platform for accessing a diverse range of nitrogen-containing functional groups such as primary amides, sulfonamides, primary amines, N-acyl compounds (esters, thioesters, amides), and N-sulfonyl esters. The method has potential industrial applicability, as demonstrated through gram-scale syntheses in batch and in a continuous flow system.
Structural, Mechanistic, Spectroscopic, and Preparative Studies on the Lewis Base Catalyzed, Enantioselective Sulfenofunctionalization of Alkenes
Hartmann, Eduard,Denmark, Scott E.
, (2017/09/19)
The full details of mechanistic investigation on enantioselective sulfenofunctionalization of alkenes under Lewis base catalysis are described. Solution spectroscopic identification of the catalytically active sulfenylating agent has been accomplished along with the spectroscopic identification of putative thiiranium ion intermediates generated in the enantiodetermining step. The structural insights gleaned from these studies informed the design of new catalyst architectures to improve enantioselectivity. In addition, structural modification of the sulfenylating agents had a significant and salutary effect on the enantioselectivity of sulfenofunctionalization which was demonstrated to be general for trans disubstituted alkenes. Whereas electronic modulation had little effect on the rate and selectivity, steric bulk on arylsulfenylphthalimides was very beneficial.
Intramolecular excimer fluorescence from folded ground state rotamers of N,N′dimethyl-N,N′-dipyrenylurea protophanes
Lewis, Frederick D.,Kurth, Todd L.
, p. 770 - 776 (2007/10/03)
The molecular structure, absorption, and fluorescence spectra of N,N′-dimethyl-N,N′-di-1-pyrenylurea and N,N′ -dimethyl-N,N′-di-2-pyrenylurea have been investigated and compared to the properties of N,N,N′-trimethyl-N′-pyrenylurea model compounds. Di-1-pyrenylurea exists as a mixture of folded (E,E) syn- and anti-rotamers that interconvert via flipping of one of the pyrene rings to an unfolded (E,Z) rotamer geometry. The symmetric di-2-pyrenylurea exists as a single folded (E,E) conformation which is in equilibrium with a less-stable, unfolded (E,Z) rotamer. The absorption and fluorescence spectra of the dipyrenylureas at 77 K in a rigid glass are similar to those of monopyrenylurea model compounds. However, in fluid solution, the dipyrenylureas exhibit excimer fluorescence and very weak monomer fluorescence which have identical decay times. This behavior is attributed to fast rotational equilibrium between folded rotamers which exhibit excimer fluorescence and unfolded rotamers which exhibit monomer fluorescence. The behavior of the dipyrenylureas is compared with that of other systems that form intramolecular pyrene excimers and diarylureas.
Chemical process
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, (2008/06/13)
Aromatic amines (e.g., aniline) are selectively alkylated in an ortho nuclear position by reaction with an olefin (e.g., ethylene) in the presence of an aluminum anilide catalyst. Hydrogen halides (e.g., HCl) are added to increase the reaction rate.
Manufacture of aromatic amino compounds
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, (2008/06/13)
A process for producing an aromatic amine comprises heating an aromatic sulfonate and a metal amide in liquid ammonia in a closed reactor at a temperature of at least 40° C to produce a metal arylamide and reacting the resultant metal arylamide with water or lower aliphatic alcohol to produce an aromatic amine.
