65918-90-3Relevant academic research and scientific papers
FT-IR study of the conformation and proton acceptor ability of N-tertiobutoxycarbonylsarcosine N'-methylamide and N-tertiobutoxycarbonylsarcosine N',N'-dimethylacetamide
Parmentier, J.,Samyn, C.,Zeegers-Huyskens, Th.
, p. 1091 - 1100 (1992)
Two model dipeptides, N-tertiobutoxycarbonylsarcosine N'-methylamide (BSMA) and N-tertiobutoxycarbonylsarcosine N',N'-dimethylamide (BSDA) are investigated by FT-IR spectrometry.The conformation of BSMA is very sensitive to the environment.In solvents of weak polarity (carbon tetrachloride, cyclohexane), BSMA accomodates the extended and seven-membered ring conformation, but in 1,2-dichloroethane, the C7 conformers are greatly destabilized.Hydrogen bonding between BSMA or BSDA and phenols is studied in carbon tetrachloride.The thermodynamic data (equilibrium constants and enthalpies of complex formation) show that the BSMA complexes are stronger than the BSDA complexes.The spectroscopic data suggest that for BSMA, complex formation occurs at the O atom of the amide function while for BSDA about 50percent of the complexes are formed on the O atom of the urethane group.The differences between the two sarcosine dipeptides are discussed in terms of cooperative and steric effects.It can be concluded that the global polarity of the medium exerts a greater influence on the conformation of the C7 dipeptides than the specific interactions taking place on a given site of the molecule.
A General Strategy to Enhance Donor-Acceptor Molecules Using Solvent-Excluding Substituents
Asbury, John B.,Hoelzel, Conner A.,Hu, Hang,Jung, Kwan Ho,Karim, Basel A.,Li, Xiaosong,Liu, Yu,Munson, Kyle T.,Wolstenholme, Charles H.,Yennawar, Hemant P.,Zhang, Han,Zhang, Xin
supporting information, p. 4785 - 4792 (2020/02/11)
While organic donor-acceptor (D-A) molecules are widely employed in multiple areas, the application of more D-A molecules could be limited because of an inherent polarity sensitivity that inhibits photochemical processes. Presented here is a facile chemical modification to attenuate solvent-dependent mechanisms of excited-state quenching through addition of a β-carbonyl-based polar substituent. The results reveal a mechanism wherein the β-carbonyl substituent creates a structural buffer between the donor and the surrounding solvent. Through computational and experimental analyses, it is demonstrated that the β-carbonyl simultaneously attenuates two distinct solvent-dependent quenching mechanisms. Using the β-carbonyl substituent, improvements in the photophysical properties of commonly used D-A fluorophores and their enhanced performance in biological imaging are shown.
