Sensing Flashcards
What is sensing?
The reporting of the binding of a guest by alteration of a macroscopic property of the host system
What are macroscopic properties?
Electrochemical
Optical
How is a sensor made from a receptor?
DIAGRAM
Incorporate an appropriate reporter group
What is the requirement of a reporter group?
Redox-active group must possess a reversible redox couple
Give an example of reporter group. Explain why it is suitable
Ferrocene
Reversible Fc/Fc+ couple
Relatively stable
Well established chemistry of functionalisation
Give two examples of ferrocene reporter groups
DIAGRAM
What is measured?
Addition of a guest leads to a shift in Fc/Fc+
What shift happens if guest is anionic or cationic? Why?
Anionic - cathodic (left) shift. Easier to oxidise Fc because this stabilises positive charge
Cationic - anodic (right) shift. Destabilises as charges repel so it is easy to reduce as this removes repulsive effect
How is E unbound related to E bound?
+nFEunbound - RTlnKox - nFEbound + RTlnKneut = 0
nF (Ebound - Eunbound) = RTln (kneut/kox)
What is an alternative electrochemical sensor?
Ion-selective electrode (contains redox inactive receptor)
What are the two types of optical sensing?
Fluorescent
Colorimetric
What is measured in fluorescent sensing?
Monitor an enhancement of quenching of the emission at a given wavelength
What is measure in colorimetric sensing?
Observe a colour change
What is an alternative strategy to optical sensing?
Indicator-displacement assays
