Conformationally restricted dinucleotide monomers and oligonucleotides

An oligonucleotide comprising at least one monomer of formula (V):

• or isomers thereof,
• wherein:
• each B is independently H or a nucleobase;
• each R is independently for each occurrence H, halo, OR3, O—(CH2)l—R4, O(CH2CH2O)mCH2CH2OR3, OCH2CH2OCH3, NH2, alkylamino, dialkylamino, heterocyclyl, arylamino, diaryl amino, heteroaryl amino, diheteroaryl amino, amino acid, NH(CH2CH2NH)nCH2CH2—R4, NHC(O)R3, cyano, mercapto, alkyl-thio-alkyl, thioalkoxy, alkyl, cycloalkyl, aryl, heteroaryl, alkenyl, or alkynyl, each of which may be optionally substituted;
• Q is independently for each occurrence CH2, —C(R6)═C(R6)—, —C≡C—, —N═CH—, —CH═N—, —O—, —S—, —S—S—, —N(R′)—C(Z)—, —C(Z)—N(R′)—, —N(R′)—C(Z)—O—, —O—C(Z)—N(R′)—, —C(O)N(R′)—N═C(R6)—;
• —N(R′)—N═C(R6)—;
• —O—N═C(R6)—, —C(R6)═N—O—, —C(R6)═N—N(R′)C(O)—, —C(R6)═N—N(R′)—, —C(R6)═N—N(R′)—O—, —O—N(R′)—N═C(R6)—,
• each R3 is independently for each occurrence H, alkyl, cycloalkyl, heterocycly, aryl, aralkyl, heteroaryl, sugar, or R4;
• each R4 is independently for each occurrence NH2, alkylamino, dialkylamino, heterocyclyl, arylamino, diaryl amino, heteroaryl amino, or diheteroaryl amino;
• R6 is H, alkyl, ω-amino alkyl, ω-hydroxy alkyl, aryl, heterocyclic, or aralkyl;
• R7 is H or
• X, X2, X3, X4 and X5 are each independently for each occurrence H, O−, OR5, S−, SR5, N(R′)(R″), B(R5)3, BH3−, or Se;
• Y, Y2, Y3, Y4 and Y5 are each independently for each occurrence O or S,
• Z and Z4 are independently for each occurrence O, S, or N(R′)(R″);
• Z5 is independently for each occurrence O, S, CH2, NR′;
• R5 is independently for each occurrence H, alkyl, cycloalkyl, heterocycly, aryl, aralkyl, or heteroaryl;
• R′ and R″ are independently for each occurrence H, alkyl, aryl, ω-amino alkyl, ω-hydroxy alkyl, ω-hydroxy alkenyl, alkynyl, cyclic alkyl, heterocyclic, aryl, or heteroaryl;
• l is independently for each occurrence 1-6;
• m is independently for each occurrence 0-50;
• n is independently for each occurrence 0-50;
• p is independently for each occurrence 0, 1, 2, 3, 4, 5, or 6;
• q is independently for each occurrence 0, 1, 2, 3, 4, 5, or 6;
• and
• r is 0, 1 or 2.