TY - JOUR
T1 - Investigation of the coordination interactions of S-(Pyridin-2-ylmethyl)-L- cysteine ligands with M(CO)3+ (M = Re, 99mTc)
AU - Haiyang, He
AU - Morley, Jennifer E.
AU - Twamley, Brenden
AU - Groeneman, Ryan H.
AU - Bucar, Dejan Kresimir
AU - MacGillivray, Leonard R.
AU - Benny, Paul D.
PY - 2009/11/16
Y1 - 2009/11/16
N2 - Development of new ligands for feo-M(OH2)3(CO) 3+ (M = Re, 99mTc) led the investigation with S-(pyridin-2-ylmethyl)L-cysteine, 1. The ligand 1 has potential to coordinate with the metal through three different tridentate modes: tripodal through cysteine (O,N,S) and two linear involving the S-pyridyl and cysteine (O,S,N Py, N,S,NPy). From the reaction with 1, two species were observed in the 1H NMR, where the primary product was the linear feo-Re(N,S, Npy-1 XCO)3-, 2a, complex. To identify the coordination mode of the minor product, functionalized analogues of 1 were prepared from S-(pyridin-2-ylmethyl)-Boc-L-cysteine-methyl ester, 3, with orthogonal protecting groups on the C terminus (methyl ester) in S-(pyridin-2-ylmethyl)-L-cysteine methyl ester, 4, or N terminus (Boc) in S-(pyridin2-ylmethyl)-Boc-L-cysteine, 6, that specifically directed the coordination mode of IaO-M(H2O)3(CO)3+ to either N1S, Npy or O,S,NPy, respectively. Two diastereomers [feo-Re(CO) 3(N,S,NPy-4)]+, 5a and 5b, were observed and independently characterized by X-ray structure analysis and NMR in high yield with 4. Surprisingly, the O,S,NPy Re complex with ligand 6 was not observed and simplified versions, 3-(pyridin-2-ylmethylthio) propanoic acid, 7, and 2-(pyridin-2-ylmethylthio)acetic acid, 8, were investigated. Ligand 7 did not yield the desired linear tridentate O,S,NPy product. However, the shorter ligand 8 formed fec-Re(CO)3(O,S,NPy-8), 9, in high yield. 99mTc labeling studies were conducted and yielded similar results to the rhenium complex and effective (>99%) at 10-5 M ligand concentration.
AB - Development of new ligands for feo-M(OH2)3(CO) 3+ (M = Re, 99mTc) led the investigation with S-(pyridin-2-ylmethyl)L-cysteine, 1. The ligand 1 has potential to coordinate with the metal through three different tridentate modes: tripodal through cysteine (O,N,S) and two linear involving the S-pyridyl and cysteine (O,S,N Py, N,S,NPy). From the reaction with 1, two species were observed in the 1H NMR, where the primary product was the linear feo-Re(N,S, Npy-1 XCO)3-, 2a, complex. To identify the coordination mode of the minor product, functionalized analogues of 1 were prepared from S-(pyridin-2-ylmethyl)-Boc-L-cysteine-methyl ester, 3, with orthogonal protecting groups on the C terminus (methyl ester) in S-(pyridin-2-ylmethyl)-L-cysteine methyl ester, 4, or N terminus (Boc) in S-(pyridin2-ylmethyl)-Boc-L-cysteine, 6, that specifically directed the coordination mode of IaO-M(H2O)3(CO)3+ to either N1S, Npy or O,S,NPy, respectively. Two diastereomers [feo-Re(CO) 3(N,S,NPy-4)]+, 5a and 5b, were observed and independently characterized by X-ray structure analysis and NMR in high yield with 4. Surprisingly, the O,S,NPy Re complex with ligand 6 was not observed and simplified versions, 3-(pyridin-2-ylmethylthio) propanoic acid, 7, and 2-(pyridin-2-ylmethylthio)acetic acid, 8, were investigated. Ligand 7 did not yield the desired linear tridentate O,S,NPy product. However, the shorter ligand 8 formed fec-Re(CO)3(O,S,NPy-8), 9, in high yield. 99mTc labeling studies were conducted and yielded similar results to the rhenium complex and effective (>99%) at 10-5 M ligand concentration.
UR - http://www.scopus.com/inward/record.url?scp=70450179470&partnerID=8YFLogxK
U2 - 10.1021/ic901159r
DO - 10.1021/ic901159r
M3 - Article
C2 - 19842652
AN - SCOPUS:70450179470
SN - 0020-1669
VL - 48
SP - 10625
EP - 10634
JO - Inorganic Chemistry
JF - Inorganic Chemistry
IS - 22
ER -