Autor: |
Mang A; Chemistry Department, University of Konstanz, 78457 Konstanz, Germany. rainer.winter@uni-konstanz.de., Rotthowe N; Chemistry Department, University of Konstanz, 78457 Konstanz, Germany. rainer.winter@uni-konstanz.de., Beltako K; Physics Department, University of Lomé, 1515 Lomé, Togo.; Institute of Physics, University of Augsburg, 86159 Augsburg, Germany. fabian.pauly@uni-a.de., Linseis M; Chemistry Department, University of Konstanz, 78457 Konstanz, Germany. rainer.winter@uni-konstanz.de., Pauly F; Institute of Physics, University of Augsburg, 86159 Augsburg, Germany. fabian.pauly@uni-a.de., Winter RF; Chemistry Department, University of Konstanz, 78457 Konstanz, Germany. rainer.winter@uni-konstanz.de. |
Abstrakt: |
The ability to predict the conductive behaviour of molecules, connected to macroscopic electrodes, represents a crucial prerequisite for the design of nanoscale electronic devices. In this work, we investigate whether the notion of a negative relation between conductance and aromaticity (the so-called NRCA rule) also pertains to quasi-aromatic and metallaaromatic chelates derived from dibenzoylmethane (DBM) and Lewis acids (LAs) that either do or do not contribute two extra d π electrons to the central resonance-stabilised β-ketoenolate binding pocket. We therefore synthesised a family of methylthio-functionalised DBM coordination compounds and subjected them, along with their truly aromatic terphenyl and 4,6-diphenylpyrimidine congeners, to scanning tunneling microscope break-junction (STM-BJ) experiments on gold nanoelectrodes. All molecules share the common motif of three π-conjugated, six-membered, planar rings with a meta -configuration at the central ring. According to our results, their molecular conductances fall within a factor of ca. 9 in an ordering aromatic < metallaaromatic < quasi-aromatic. The experimental trends are rationalised by quantum transport calculations based on density functional theory (DFT). |