nl5010702_si_001.pdf (1.95 MB)
Breakdown of Interference Rules in Azulene, a Nonalternant Hydrocarbon
journal contribution
posted on 2014-05-14, 00:00 authored by Jianlong Xia, Brian Capozzi, Sujun Wei, Mikkel Strange, Arunabh Batra, Jose R. Moreno, Roey J. Amir, Elizabeth Amir, Gemma
C. Solomon, Latha Venkataraman, Luis M. CamposWe have designed and synthesized
five azulene derivatives containing
gold-binding groups at different points of connectivity within the
azulene core to probe the effects of quantum interference through
single-molecule conductance measurements. We compare conducting paths
through the 5-membered ring, 7-membered ring, and across the long
axis of azulene. We find that changing the points of connectivity
in the azulene impacts the optical properties (as determined from
UV–vis absorption spectra) and the conductivity. Importantly,
we show here that simple models cannot be used to predict quantum
interference characteristics of nonalternant hydrocarbons. As an exemplary
case, we show that azulene derivatives that are predicted to exhibit
destructive interference based on widely accepted atom-counting models
show a significant conductance at low biases. Although simple models
to predict the low-bias conductance do not hold with all azulene derivatives,
we demonstrate that the measured conductance trend for all molecules
studied actually agrees with predictions based on the more complete
GW calculations for model systems.