Patent ID: 8536323

Claim:
A compound having the structure (I): or a salt, conjugate base, tautomer, or ionized form thereof, wherein P1 is a phosphate group; P2 is a phosphate group; Nus is a nucleoside moiety comprising a sugar bound to a purine or pyrimidine base; Alk is a connecting group having the structure —//—(CH 2 ) m —Y—//— where Y is a bond or bond forming group selected from and m is an integer ranging from 3 to 6 inclusive, and wherein the leftmost bond is to Nus and the rightmost bond is to Lnk; Lnk is a linking group having the structure where n is an integer ranging from 2 to 48 inclusive; A 1 is a bond forming group selected from A 2 is a bond forming group selected from A 3 , when present, is a bond forming group selected from and X is a cleavable group that can undergo silicon-carbon cleavage, nucleophilic cleavage, redox cleavage, photochemical cleavage, enzymatic cleavage, or exchange-based cleavage, and the leftmost bond is to Alk and the rightmost bond is to Obs; and Obs is an observable label.