Organic Synthesis

  • Photochromic and Light-harvesting Molecules
  • Redox-active Molecules
  • Donor-Acceptor Molecules (charge-transfer systems)
  • Molecular Wires and Switches
  • π-Conjugated Oligomers and Macrocycles

Photochromic and Light-harvesting Molecules - "Solar Heat Batteries"

One goal is to develop photochromic molecules that can harvest sunlight, store the energy in chemical bonds via photo-isomerization reactions, and release the energy again when needed. In particular, we work on tuning the properties of the dihydroazulene (DHA) / vinylheptafulvene (VHF) photo/thermoswitch. DHA undergoes a light-induced ring-opening reaction to generate VHF, which in time returns to DHA. By suitable functionalization, we aim at controlling both the amount of energy stored in the meta-stable VHF isomer and the rate of the VHF to DHA back-reaction. For example, both the ring-opening and ring-closure reactions are stongly influenced by electron-donating or withdrawing substituents placed in either the five- og seven-memberede ring of DHA.

We have particular focus on using metal-catalyzed cross-coupling reactions, such as the Suzuki coupling, for functionalizing the DHA core. By a bromination / elimination / cross-coupling protocol, an acryl substituent is readily incorporated regioselectively in the seven-membered ring of DHA:

In a related project, we are developing photoresponsive liquid crystals based on the DHA/CHF system - click for more information

Selected Publications:

  • "Arylethynyl Derivatives of the Dihydroazulene / Vinylheptafulvene Photo / Thermoswitch - Tuning the Switching Event", J.Am.Chem.Soc. 2010, 132,9265-9174.
  • "Gaining control. Direct Suzuki Arylation of Dihydroazulenes and Tuning of Photo/Thermochromism", Eur.J.Org.Chem. 2011,1033-1039.
  • "Dihydroazulene Photoswitch operating in Sequential Tunneling Regime: Synthesis and Single-Molecule Junction Studies", Adv.Funct.Mater. 2012,224249-4258.
  • "Ultrathin Reduced Graphene Oxide Films as Transparante Top-Contacts for Light Switchable Solid-State Molecular Junctions", Adv.Mater. 2013,25,4264-4170.
  • "Palladium-mediated Strategies for Functionalizing the dihydroazulene Photoswitch: Paving the Way for its Exploitation in Molecular Electronics", J.Org.Chem. 2013,78,4348-4356.
  • "Linear Free-energy Correlations for the Vinylheptafulvene Ring Closure: a Probe for Hammett values", Chem.Eur.J. 2013,19,9542-9548.
  • "Syntheses of Donor-Acceptor Functionalized Dihydroazulenes", J.Org.Chem. 2014,79,41-64.
  • "CuAAC and RuAAC with Alkyne-functionalissed Dihydroazulene Photoswitches and Determination of Hammett -Constants for Triazoles", Aust.J.Chem. 2014,67,531-534.
  • "Synthetic protocols for the key functionlizations of the photochromic dihydroazylene scaffold", Arkivoc 2014,i, 249-263.