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Material Clocking by Silica Nanoparticle Precipitation in Solution Phase that is Tunable by Organic Molecules
Author(s) -
Miyagawa Masamichi,
Yamaguchi Masahiko
Publication year - 2015
Publication title -
chempluschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.801
H-Index - 61
ISSN - 2192-6506
DOI - 10.1002/cplu.201500300
Subject(s) - precipitation , suspension (topology) , dispersion (optics) , nanoparticle , materials science , chemical engineering , molecule , phase (matter) , colloid , flocculation , nanotechnology , chemistry , organic chemistry , optics , mathematics , homotopy , physics , engineering , meteorology , pure mathematics
Material clocking is an important biological phenomenon through which the structure of a material changes sharply with time after activation. A suspension of silica ( P )‐nanoparticles in the presence of organic molecules in solution exhibits such a material clocking phenomenon during delayed precipitation with high accuracy and precision. A mixture of ethynylhelicene ( P )‐pentamer and silica ( P )‐nanoparticles with an average diameter of 70 nm grafted with ( P )‐helicene in trifluoromethylbenzene is sonicated for activation and dispersion. The ( P )‐nanoparticles start to precipitate after 3 h of settling at 25 °C and precipitate completely after 4 h. UV/Vis, CD, and DLS analyses of the process show no change during the initial 3 h, but then an abrupt stair‐shaped kinetic change occurs with concomitant precipitation and removal of the ( P )‐pentamer from the solution phase. The delay in the precipitation can be tuned by the structure of molecules added to the ( P )‐nanoparticle suspension.