%0 Journal Article
%A Zhou, Yuntao
%A Li, Lijie
%A Ye, Hebo
%A Zhang, Ling
%A You, Lei
%D 2016
%T Quantitative
Reactivity Scales for Dynamic Covalent
and Systems Chemistry
%U https://acs.figshare.com/articles/journal_contribution/Quantitative_Reactivity_Scales_for_Dynamic_Covalent_and_Systems_Chemistry/2089132
%R 10.1021/jacs.5b11361.s001
%2 https://ndownloader.figshare.com/files/3722347
%K DCC
%K RE
%K RN
%K DCR
%K Quantitative Reactivity Scales
%K correlation log K
%K reactivity scales
%K Systems ChemistryDynamic covalent chemistry
%K EWG
%K imine
%K EDG
%K SN
%K parameter
%X Dynamic
covalent chemistry (DCC) has become a powerful tool for
the creation of molecular assemblies and complex systems in chemistry
and materials science. Herein we developed for the first time quantitative
reactivity scales capable of correlation and prediction of the equilibrium
of dynamic covalent reactions (DCRs). The reference reactions are
based upon universal DCRs between imines, one of the most utilized
structural motifs in DCC, and a series of O-, N-, and S- mononucleophiles.
Aromatic imines derived from pyridine-2-carboxyaldehyde exhibit capability
for controlling the equilibrium through distinct substituent effects.
Electron-donating groups (EDGs) stabilize the imine through quinoidal
resonance, while electron-withdrawing groups (EWGs) stabilize the
adduct by enhancing intramolecular hydrogen bonding, resulting in
curvature in Hammett analysis. Notably, unique nonlinearity induced
by both EDGs and EWGs emerged in Hammett plot when cyclic secondary
amines were used. This is the first time such a behavior is observed
in a thermodynamically controlled system, to the best of our knowledge.
Unified quantitative reactivity scales were proposed for DCC and defined
by the correlation log K = SN (RN + RE). Nucleophilicity
parameters (RN and SN) and electrophilicity parameters
(RE) were then developed
from DCRs discovered. Furthermore, the predictive power of those parameters
was verified by successful correlation of other DCRs, validating our
reactivity scales as a general and useful tool for the evaluation
and modeling of DCRs. The reactivity parameters proposed here should
be complementary to well-established kinetics based parameters and
find applications in many aspects, such as DCR discovery, bioconjugation,
and catalysis.
%I ACS Publications