title: Attaching high charge density metal ions to surfaces and biomolecules. Reaction chemistry of hypodentate cobalt diamine complexes.
abstract: Hypodentate diamine cobalt(III) pentammine complexes [Co(NH3)5(NH2(CH2)(n)NH3)](ClO4)4 (8: a: n = 3; b: n = 4; c: n = 6; d: n = 8) have been synthesized via the reaction of [Co(NH3)5(OTf)](OTf)2 (TfOH = CF3SO3H) with the corresponding diamines. The analogous t-boc protected diamine complexes [Co(NH3)5(NH2(CH2)(n)NHt-boc)](ClO4)3 (7a-d) were prepared in 4-26% yield. Low yields for the formation of 7a-d are due to competing side reactions which also gave [Co(NH3)6](3+). Complexes 7a-d were deprotected using trifluoroacetic acid to give the corresponding hypodentate diamine complexes [Co(NH3)5(NH2(CH2)(n)NH3)](CF3CO2)0.5(ClO4)3.5 (9a-d). HBTU coupling of 8c with N-(t-boc)-L-phenylalanine gave an amino acid functionalized cobalt pentammine complex [Co(NH3)5(NH2(CH2)6NHt-boc)-L-phenylalanine)](ClO4)3 (10). All new complexes were characterized using UV-vis and (1)H NMR spectroscopy, and elemental analysis. Grafting of 8c onto 2.4 mm poly(ethylene-co-acrylic acid) (PEAA) beads was achieved via amide coupling. Complex 8c was coupled to thioctic acid via amide coupling and the resulting cobalt disulfide complex [Co(NH3)5(N-(6-aminohexyl)-5-(1,2-dithiolan-3-yl)pentanamide)](ClO4)3 (11) was attached to 10 nm Au nanoparticles. The amount of cobalt loading onto PEAA beads and Au nanoparticles was determined using ICP-MS and EDX.
authors.affiliation: Chemistry Department, Florida Institute of Technology, 150 University Boulevard, Melbourne, FL 32901, USA. aknight@fit.edu.
authors.forename: Aaron R
authors.initials: AR
authors.lastname: Funk
authors.forename: Efram
authors.initials: E
authors.lastname: Goldberg
authors.forename: Eddie L
authors.initials: EL
authors.lastname: Chang
authors.forename: Scott A
authors.initials: SA
authors.lastname: Trammell
authors.forename: D Andrew
authors.initials: DA
authors.lastname: Knight
mesh_terms: D000588:Amines / Q000737:chemistry*; D003035:Cobalt / Q000737:chemistry*; D006046:Gold / Q000737:chemistry; D053768:Metal Nanoparticles / Q000737:chemistry; D008863:Microspheres; D009942:Organometallic Compounds / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry; D013499:Surface Properties
chemical_list: D000588:Amines; D009942:Organometallic Compounds; D011108:Polymers; D003035:Cobalt; D006046:Gold