Rb is, independently at each occurrence, C1 6 alkyl, ORa, Cl, F, Br, NRaRa1, CRa, {HEAD ~ CORa}, CNRaRa1, S2NRaRa1, NRaS2Ra3, {TAIL ~ SpRa3}, or CF3 
Rb is , independently at each occurrence , C1 6 alkyl , ORa , Cl , F , Br , NRaRa1 , CRa , { HEAD ~ CORa } , CNRaRa1 , S2NRaRa1 , NRaS2Ra3 , { TAIL ~ SpRa3 } , or CF3
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH