ERIC Number: EJ1046323
Record Type: Journal
Publication Date: 2014-Nov
Abstractor: As Provided
Reference Count: 10
Synthesis and Application of Ratiometric and "Turn-On" Fluorescent pH Sensors: An Advanced Organic Undergraduate Laboratory
Hutt, Johnathon T.; Aron, Zachary D.
Journal of Chemical Education, v91 n11 p1990-1994 Nov 2014
An upper-division organic chemistry laboratory experiment exploring fluorescent sensing over two laboratory periods and part of a third is described. Two functionally distinct pH-responsive sensors are prepared through a dehydrative three-component coupling reaction. During the abbreviated (<1 h) first laboratory period, students set up reactions to prepare the two compounds. The second period involves purification using salt metathesis and characterization using standard techniques. The third period is spent exploring the fluorescent characteristics of the two compounds through visual (eye) and fluorometer analysis of solutions at varying pH. The two sensors show either a "turn-on" (photoinduced electron transfer, PET) or "ratiometric" (intramolecular charge transfer, ICT) response to protonation with these distinctions deriving from sterically induced differences in conformation. This experiment is appropriate for demonstrating steric effects on reactivity and macroscopic properties, multicomponent coupling reactions, carbonyl reactivity, aromatization, purification of ionic organic molecules, absorbance and emission of light by organic molecules, frontier molecular orbital theory, and fluorescence sensing.
Descriptors: Science Instruction, College Science, Undergraduate Study, Organic Chemistry, Science Experiments, Science Laboratories, Scientific Concepts, Molecular Structure, Hands on Science, Spectroscopy, Laboratory Experiments
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Publication Type: Journal Articles; Reports - Descriptive
Education Level: Higher Education; Postsecondary Education
Authoring Institution: N/A