{TAIL ~ An additional objective} is to provide molecular structures with high rotational flexibility between {HEAD ~ the silicon atoms} and the planar configurations of the aromatic moieties to permit tight bonding of the molecule to the substrate 
{ TAIL ~ An additional objective } is to provide molecular structures with high rotational flexibility between { HEAD ~ the silicon atoms } and the planar configurations of the aromatic moieties to permit tight bonding of the molecule to the substrate
TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH