Patent ID: 7291647

Claim:
A compound, having the formula: or a salt thereof; wherein X 3 and X 4 each independently represent GhyCH— or GhyCCH 3 —; wherein Z is a group having the formula —A—(CH 2 ) p —A—, wherein p is 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, and wherein the A's are each independently —NH(CO)—, —(CO)NH—, or —NH(CO)NH— groups; or wherein Z is a group having the formula —A—(C 6 H 4 )—A—, wherein the A's are each independently —CO—, —NH(CO)—, —(CO)NH—, or —NH(CO)NH— groups; or wherein Z is a group having the formula: or wherein Z is a group having the formula: or wherein Z is a group having the formula: or wherein Z is a group having the formula: or wherein Z is a group having the formula: or wherein Z is a group having the formula: or wherein Z is a group having the formula: or wherein Z is a group having the formula: