Environmental Applications of ESI FT-ICR Mass Spectrometry Oxidized Peptide and Metal Sulfide Clusters Dissertation Defense January 7, 2010 Jeffrey M. Spraggins University of Delaware Department of Chemistry & Biochemistry Advisor: Douglas Ridge, Ph.D. Gas Phase Ion-Molecule Reactions Metal Sulfide Clusters ESI FT-ICR Mass Spectrometry Overview Oxidized Peptides Johnston Group Dr. Laskin: PNNL Luther Group (Marine Studies) Fragmentation Mechanisms Energy-resolved SID Molecular Dynamics RRKM Theory Metal Sulfide Formation Molecular Capping Agents Oxidized Peptides Jeffrey M. Spraggins, Julie A. Lloyd, Murray V. Johnston, Julia Laskin, Douglas P. Ridge J.Am. Soc. Mass Spec. (2009), Accepted for puplication. Julie A. Lloyd, Jeffrey M. Spraggins, Murray V. Johnston, Julia Laskin, J. Am. Soc. Mass Spec. (2006), 17(9), ESI FT-ICR Mass Spectrometry Oxidation Reaction AngII AngII + O AngII + 3O O3O3 AngII + 4O Tyr* and His* (~143M) Tyr* His* Asp-Arg-Val-Tyr-Ile-His-Pro-Phe 6 T FT-ICR MS: PNNL Lens 1 Lens 2 Quad Bender Lens 4Lens 5Lens 3 Segmented Lenses SAM Surface 6T Magnet Deceleration Lenses Trapping Plates Ion Source Ion Funnel Torr Collisional Quadrupole mTorr Resolving Quadrupole 5 Torr Accumulation Quadrupole 2 mTorr Trapping Plates Conductance Limit Collimating Plate Laskin J.; Denisov E. V.; Shukla A. K.; Barlow S. E.; Futrell J. H. Analytical chemistry 2002, 74, Intensity m/z (b-d: 43eV SID Spectra) AngII AngII+O AngII+3O AngII+4O Asp-Arg-Val-Tyr-Ile-His-Pro-Phe y7y7 Energy Resolved FECs: AngII Collision Energy (eV) Relative Intensity y7y7 Acidic Amino Acids J. Laskin J. Futrell V. Wysocki J. Beauchamp Scheme Ia Scheme Ib AngII: charge delocalization Asp-Arg-Val- Tyr(+O) -Ile- His(+3O) -Pro-Phe b 4 +O Energy Resolved FECs: AngII+O Collision Energy (eV) Relative Intensity AngII+O b 4 fragmentation pathway Scheme II b 4 +O AngII+O: b 4 fragment Acidic Amino Acids J. Laskin J. Futrell V. Wysocki J. Beauchamp Scheme Ia Scheme Ib Asp-Arg-Val- Tyr(+O) -Ile- His(+3O) -Pro-Phe b5b5 -88 AngII+3O [MH+3O] & [MH+3O] [MH+3O] [MH+3O] Scheme III AngII+3O [MH+3O] & b 5 fragmentation pathway [MH+3O] b5b5 Scheme IV Transition States Collision Energy (eV) Relative Intensity RRKM Theory [MH+nO] + DRVYIHPFDRVY * IHPFDRVYIH * PFDRVY * IH * PF M/Z E 0 (eV) S (cal/mol K) Relative E A, s x x x x10 10 Log (A) Entropic Considerations (a) y 7 fragment (b) b 4 +O fragment (c) [AngII+3O]-45 S (cal/mol K) Side Chain Backbone Amide Bond Conclusions Unmodified Ang II Charge-remote selectivity towards y 7 fragment M+O adduct FECs suggest that the b 4 pathway is a charge-remote process. C-term Tyr * - Backbone interaction leads to b 4 fragment ion. M+3O product FECs show both charge-remote and charge-directed selective fragmentation channels are opened with the oxidation of the His residue. Loss of 45m/z and 71m/z driven by strong H-bonding within the His * side chain. His * is thought to compete with Arg for the lone proton leading to the b 5 and [MH+3O] charge-directed fragments. RRKM results imply destabilization due to entropic effects. Consistent with proposed fragmentation mechanisms for oxidation products The Big Picture Structurally characterize peptide degradation by ozone exposure Contribution to Fundamental MS/MS Literature Understanding oxidized peptide fragmentation could benefit MS protein structural research Method for increasing fragmentation sequence coverage for proteomic studies Metal Sulfide Clusters ESI FT-ICR Mass Spectrometry 10 1 Size (nm) Dissolved Ions Clusters (Dissolved Polynuclear Molecular Species) Nanoparticles (1-100nm) Solid state material Project Goal Metal Sulfide Precipitation - Cluster Aggregation Experimental Approach - Capping Agents - Ion-Molecule Reactions T. F. Rozan, M. E. Lassman, D. P. Ridge, G. W. Luther. Evidence for iron, copper and zinc complexation as multinuclear sulphide clusters in oxic rivers. Nature, 2000, 406, 10 1 Size (nm) Project Goal Mass Spectrometry UV/VIS Spectroscopy Dissolved Ions Clusters Nanoparticles Solid state material 7T FT-ICR MS: UD ESI of Metal Salt Solutions Observed Nucleation Processes Salt Clusters Observed using ESI FT-ICR MS Signal Variance [Cd(CH 3 COO) 3 ] - [Cd 2 (CH 3 COO) 5 ] - [Cd 3 (CH 3 COO) 7 ] - [Cd 4 (CH 3 COO) 9 ] - [Cd 5 (CH 3 COO) 11 ] - [Cd 6 (CH 3 COO) 13 ] - [Cd 7 (CH 3 COO) 15 ] - [Cd 8 (CH 3 COO) 17 ] - Sampling was done using separate aliquots for each spectrum and A single aliquot was continually injected as spectra were repeatedly taken. 0.3 mM cadmium acetate water/MeOH solution (1:1) Important Points Variance in signal over time suggests that clusters observed using ESI are forming in solution. Results highlight processes taking place in low dielectric constant solvents Water/MeOH ( =66 ) Hydrothermal Fluids ( =10-23 ) Akerlof, G. Dielectric Constant of some Organic Solvent-Water Mixtures at various Temperatures. J. Am. Chem. Soc. 1932, 54, Weingartner, H.; Franck, E. U. Supercritical Water as a Solvent. Angew Chem Int Ed Engl. 2005, 44, Making Metal Sulfide Clusters Molecular Capping Agents Solution Chemistry: Mononuclear Anions A)3 mM aqueous solution of Cd(NO 3 ) 2 4H 2 O diluted 50/50 with MeOH. B)1.5 mM aqueous solution of Cd(NO 3 ) 2 4H 2 O and 2- mercaptopyridine (1:1) diluted 50/50 with MeOH. C)H 2 S(g) bubbled through a 3 mM aqueous solution of Cd(NO 3 ) 2 4H 2 O followed by addition of 2-mercaptopyridine (1:1), then diluted 50/50 with MeOH. Solution Chemistry: Binuclear Anions A)3 mM aqueous solution of Cd(NO 3 ) 2 4H 2 O diluted 50/50 with MeOH. B)1.5 mM aqueous solution of Cd(NO 3 ) 2 4H 2 O and 2- mercaptopyridine (1:1) diluted 50/50 with MeOH. C)H 2 S(g) bubbled through a 3 mM aqueous solution of Cd(NO 3 ) 2 4H 2 O followed by addition of 2-mercaptopyridine (1:1), then diluted 50/50 with MeOH. Solution Chemistry: Trinuclear Anions A)3 mM aqueous solution of Cd(NO 3 ) 2 4H 2 O diluted 50/50 with MeOH. B)1.5 mM aqueous solution of Cd(NO 3 ) 2 4H 2 O and 2- mercaptopyridine (1:1) diluted 50/50 with MeOH. C)H 2 S(g) bubbled through a 3 mM aqueous solution of Cd(NO 3 ) 2 4H 2 O followed by addition of 2-mercaptopyridine (1:1), then diluted 50/50 with MeOH. Important Points Sulfidic clusters are observed when 2-mercaptopyridine is introduced. Reactivity with H 2 S is selective based on cluster size for [Cd x (NO 3 ) 2x+1 ] - species. Sampling a solution based process Gas phase ion-molecule reactions Making Metal Sulfide Clusters Gas Phase Ion-Molecule Reactions Cadmium Salt Clusters Reactive Clusters [Cd(CH 3 COO) 3 ] - [Cd 2 (CH 3 COO) 5 ] - [Cd 3 (CH 3 COO) 7 ] - [Cd 4 (CH 3 COO) 9 ] - [Cd 2 (CH 3 COO) 3 ] + [Cd 3 (CH 3 COO) 5 ] + [Cd 4 (CH 3 COO) 7 ] + [Cd 2 (NO 3 ) 5 ] - [Cd 3 (NO 3 ) 7 ] - [Cd 4 (NO 3 ) 9 ] - [CdNO 3 (CH 3 OH)] + [CdNO 3 (CH 3 OH)(H 2 O)] + [CdCl(CH 3 OH)] + [Cd 2 Cl 3 (CH 3 OH)] + [ZnCl(CH 3 OH)] + Non-Reactive Clusters [Cd(NO 3 ) 3 ] - [Cd x Cl 2x+1 ] - [Zn x Cl 2x+1 ] - [Cd 2 (NO 3 ) 5 ] - [Cd 2 SH(NO 3 ) 4 ] - [Cd 2 (SH) 2 (NO 3 ) 3 ] - H2SH2S -2HNO 3 [Cd 2 S(NO 3 ) 3 ] - {444 m/z}{507 m/z} {478 m/z} {536 m/z} -HNO 3 H2SH2S -2HNO 3 H2SH2S [Cd 2 (NO 3 ) 5 ] - [Cd 2 SH(NO 3 ) 4 ] - [Cd 2 (SH) 2 (NO 3 ) 3 ] - H2SH2S -2HNO 3 [Cd 2 S(NO 3 ) 3 ] - {444 m/z}{507 m/z} {478 m/z} {536 m/z} -HNO 3 H2SH2S -2HNO 3 H2SH2S Cd 2 S 0 Cd 2 S 1 Cd 2 S 2 [S 0 ]= [A] 0 e -k 1 t [S 1 ]= k1k1 k 2 -k 1 (e -k 1 t - e -k 2 t ) (k 2 -k 1 )(k 3 -k 1 )(k 1 -k 2 )(k 3 -k 2 )(k 1 -k 3 )(k 2 -k 3 ) e -k 1 t e -k 2 t e -k 3 t [S 2 ]= k 1 k 2 ++ [Cd 2 (NO 3 ) 5 ] - [Cd 2 (NO 3 ) 4 SH] - [Cd 2 (NO 3 ) 3 (SH) 2 ] - H2SH2S -CH 3 COOH [Cd 2 S(NO 3 ) 3 ] - {444 m/z} {507 m/z} {478 m/z} {536 m/z} H2SH2S -CH 3 COOH S0S0 S2S2 S1S1 k1k1 k2k2 k 3 = 0 r = k[Cluster Family][H 2 S] r = k[Cluster Family] H 2 S is in excess Pseudo First Order kinetics d[S 0 ] dt = -k 1 [S 0 ] d[S 1 ] dt = k 1 [S 0 ] k 2 [S 2 ] d[S 2 ] dt = k 2 [S 1 ] Integrated Rate Equations [A] 0 4x10 -9 torr [Cd 2 (NO 3 ) 5 ] - +H 2 S (g) [Cd 2 SH(NO 3 ) 4 ] - [Cd 2 S(NO 3 ) 3 ] - [Cd 2 (SH) 2 (NO 3 ) 3 ] - [Cd 2 S 0 ] - [Cd 2 S 1 ] - [Cd 2 S 2 ] - k 1 = s -1 k 2 = 0.001s -1 [Cd 2 (NO 3 ) 5 ] - +H 2 S [Cd 2 SH(NO 3 ) 4 ] - [Cd 2 S(NO 3 ) 3 ] - [Cd 2 (SH) 2 (NO 3 ) 3 ] - H 2 S: 4x10 -9 torr [Cd 2 S 0 ] - [Cd 2 S 1 ] - [Cd 2 S 2 ] - k 1 = s -1 k 2 = 0.001s -1 Reaction Efficiency Assume fastest RXN is collision rate limited [Cd(NO 3 )(CH 3 OH)] + k 1 = 2.85 0.27 s -1 Capture Collision Theory H 2 S: 4x10 -9 torr [Cd 2 S 0 ] - [Cd 2 S 1 ] - [Cd 2 S 2 ] - k 1 = s -1 k 2 = 0.001s -1 Reaction Efficiency Assume fastest RXN is collision rate limited [Cd(NO 3 )(CH 3 OH)] + k 1 = 2.85 0.27 s -1 Capture Collision Theory H 2 S: 4x10 -9 torr [Cd 2 S 0 ] - [Cd 2 S 1 ] - [Cd 2 S 2 ] - k 1 = s -1 k 2 = 0.001s -1 k 1 /k c = k 2 /k c = Reaction Efficiency Assume fastest RXN is collision rate limited [Cd(NO 3 )(CH 3 OH)] + k 1 = 2.85 0.27 s -1 Capture Collision Theory H 2 S: 4x10 -9 torr Reactant P (10 -9 torr) H (kcal/mol) k 1 /k c k 2 /k c k 3 /k c k 4 /k c k 5 /k c k 6 /k c k 7 /k c [Cd(CH 3 COO) 3 ] [Cd(CH 3 COO) 3 ] [Cd 2 (CH 3 COO) 5 ] [Cd 2 (CH 3 COO) 5 ] [Cd 3 (CH 3 COO) 7 ] [Cd 3 (CH 3 COO) 7 ] [Cd 4 (CH 3 COO) 9 ] (24) 1.00* (15) [Cd 4 (CH 3 COO) 9 ] (15) 1.00* Anionic Cadmium Clusters [Cd(NO 3 ) 3 ] - 4 & No RXN [Cd 2 (NO 3 ) 5 ] [Cd 3 (NO 3 ) 7 ] [Cd 4 (NO 3 ) 9 ] [CdCl 3 ] - 4 & No RXN [Cd x Cl 2x+1 ] - 4 & 9No RXN Reactant P (10 -9 torr) H (kcal/mol) k 1 /k c k 2 /k c k 3 /k c k 4 /k c k 5 /k c k 6 /k c k 7 /k c [Cd(CH 3 COO) 3 ] [Cd(CH 3 COO) 3 ] [Cd 2 (CH 3 COO) 5 ] [Cd 2 (CH 3 COO) 5 ] [Cd 3 (CH 3 COO) 7 ] [Cd 3 (CH 3 COO) 7 ] [Cd 4 (CH 3 COO) 9 ] (24) 1.00* (15) [Cd 4 (CH 3 COO) 9 ] (15) 1.00* Anionic Cadmium Clusters [Cd(NO 3 ) 3 ] - 4 & No RXN [Cd 2 (NO 3 ) 5 ] [Cd 3 (NO 3 ) 7 ] [Cd 4 (NO 3 ) 9 ] [CdCl 3 ] - 4 & No RXN [Cd x Cl 2x+1 ] - 4 & 9No RXN Most Anionic Metal Cluster reactions are < 5% efficient. Reactant P (10 -9 torr) H (kcal/mol) k 1 /k c k 2 /k c k 3 /k c k 4 /k c k 5 /k c k 6 /k c k 7 /k c [Cd(CH 3 COO) 3 ] [Cd(CH 3 COO) 3 ] [Cd 2 (CH 3 COO) 5 ] [Cd 2 (CH 3 COO) 5 ] [Cd 3 (CH 3 COO) 7 ] [Cd 3 (CH 3 COO) 7 ] [Cd 4 (CH 3 COO) 9 ] (24) 1.00* (15) [Cd 4 (CH 3 COO) 9 ] (15) 1.00* Anionic Cadmium Clusters [Cd(NO 3 ) 3 ] - 4 & No RXN [Cd 2 (NO 3 ) 5 ] [Cd 3 (NO 3 ) 7 ] [Cd 4 (NO 3 ) 9 ] [CdCl 3 ] - 4 & No RXN [Cd x Cl 2x+1 ] - 4 & 9No RXN The Exception [Cd 4 (CH 3 COO) 9 ] - [Cd 4 (CH 3 COO) 8 SH] - [Cd 4 (CH 3 COO) 7 (SH) 2 ] - H2SH2S -2CH 3 COOH H2SH2S -CH 3 COOH [Cd 4 (CH 3 COO) 7 S] - [Cd 4 (CH 3 COO) 6 S(SH)] - -CH 3 COOH {894 m/z} {980 m/z} H2SH2S -CH 3 COOH {954 m/z} {868 m/z}{928 m/z} H2SH2S -CH 3 COOH [Cd 4 (CH 3 COO) 4 S 2 ] - -CH 3 COOH{808 m/z} [Cd 4 (CH 3 COO) 6 (SH) 3 ] - [Cd 4 (CH 3 COO) 5 S(SH) 2 ] - -CH 3 COOH H2SH2S {842 m/z} {902 m/z} H2SH2S -CH 3 COOH [Cd 4 (CH 3 COO) 4 S 2 (SH)] - -CH 3 COOH {782 m/z} H2SH2S -CH 3 COOH [Cd 4 (CH 3 COO) 3 S 3 ] - -CH 3 COOH {722 m/z} [Cd 4 (CH 3 COO) 5 (SH) 4 ] - [Cd 4 (CH 3 COO) 4 S(SH) 3 ] - -CH 3 COOH H2SH2S {816 m/z} {876 m/z} H2SH2S -CH 3 COOH [Cd 4 (CH 3 COO) 3 S 2 (SH) 2 ] - -CH 3 COOH{756 m/z} H2SH2S -CH 3 COOH [Cd 4 (CH 3 COO) 2 S 3 (SH)] - -CH 3 COOH{696 m/z} H2SH2S -CH 3 COOH [Cd 4 (CH 3 COO) 4 (SH) 5 ] - [Cd 4 (CH 3 COO) 3 S(SH) 4 ] - -CH 3 COOH H2SH2S {790 m/z} {850 m/z} H2SH2S -CH 3 COOH [Cd 4 (CH 3 COO) 2 S 2 (SH) 3 ] - -CH 3 COOH {730 m/z} H2SH2S -CH 3 COOH [Cd 4 (CH 3 COO)S 3 (SH) 2 ] - -CH 3 COOH {670 m/z} H2SH2S -CH 3 COOH [Cd 4 (CH 3 COO) 3 (SH) 6 ] - [Cd 4 (CH 3 COO) 2 S(SH) 5 ] - -CH 3 COOH H2SH2S {764 m/z} {824 m/z} H2SH2S -CH 3 COOH [Cd 4 (CH 3 COO)S 2 (SH) 4 ] - -CH 3 COOH{704 m/z} H2SH2S -CH 3 COOH [Cd 4 S 3 (SH) 3 ] - -CH 3 COOH {644 m/z} H2SH2S -CH 3 COOH [Cd 4 (CH 3 COO) 2 (SH) 7 ] - [Cd 4 (CH 3 COO)S(SH) 6 ] - -CH 3 COOH H2SH2S {738 m/z} {798 m/z} H2SH2S -CH 3 COOH [Cd 4 S(SH) 5 ] - -CH 3 COOH {678 m/z} H2SH2S -CH 3 COOH [Cd 4 (CH 3 COO)(SH) 8 ] - [Cd 4 S(SH) 7 ] - -CH 3 COOH H2SH2S {712 m/z} {772 m/z} H2SH2S -CH 3 COOH [Cd 4 (CH 3 COO) 9 ] - +H 2 S (g) [Cd 4 S 0 ] - [Cd 4 S 1 ] - [Cd 4 S 2 ] - [Cd 4 S 3 ] - [Cd 4 S 4 ] - [Cd 4 S 5 ] - [Cd 4 S 6 ] - k 1 /k c = k 2 /k c = k 3 /k c = 1.0* k 4 /k c = 1.0* k 5 /k c = 1.0* k 6 /k c = [Cd 4 S 7 ] - k 7 /k c = k 1 /k c = k 2 /k c = k 3 /k c = 1.0* k 4 /k c = 1.0* k 5 /k c = 1.0* k 6 /k c = k 7 /k c = [Cd 4 S(CH 3 COO) 9 ] - [Cd 4 S 2 (SH) 3 (CH 3 COO) 2 ] - [Cd 4 S 2 (SH) 4 (CH 3 COO)] - [Cd 4 S 3 (SH) 3 ] - [Cd 4 S 2 (SH) 5 ] - 4x10 -9 torr 9x10 -9 torr [Cd 4 S(CH 3 COO) 9 ] - [Cd 4 S 2 (SH) 3 (CH 3 COO) 2 ] - [Cd 4 S 2 (SH) 4 (CH 3 COO)] - [Cd 4 S 3 (SH) 3 ] - [Cd 4 (CH 3 COO) 9 ] - +H 2 S (g) [Cd 4 S 2 (SH) 5 ] - Reactant P (10 -9 torr) H (kcal/mol) k 1 /k c k 2 /k c k 3 /k c k 4 /k c k 5 /k c k 6 /k c k 7 /k c [Cd(CH 3 COO) 3 ] [Cd(CH 3 COO) 3 ] [Cd 2 (CH 3 COO) 5 ] [Cd 2 (CH 3 COO) 5 ] [Cd 3 (CH 3 COO) 7 ] [Cd 3 (CH 3 COO) 7 ] [Cd 4 (CH 3 COO) 9 ] (24) 1.00* (15) [Cd 4 (CH 3 COO) 9 ] (15) 1.00* Anionic Cadmium Clusters [Cd(NO 3 ) 3 ] - 4 & No RXN [Cd 2 (NO 3 ) 5 ] [Cd 3 (NO 3 ) 7 ] [Cd 4 (NO 3 ) 9 ] [CdCl 3 ] - 4 & No RXN [Cd x Cl 2x+1 ] - 4 & 9No RXN Calculated reaction enthalpies are consistent with observed reactivity. Cationic Metal Sulfide Clusters [Cd 4 (CH 3 COO) 7 ] + + H 2 S SH - Substitution CH 3 COOH Elimination H 2 S Addition [Cd 4 (CH 3 COO) 7 ] + +H 2 S (g) [Cd 4 SH(CH 3 COO) 6 ] + [Cd 4 (SH) 3 (CH 3 COO) 4 ] + [Cd 4 S(SH) 2 (CH 3 COO) 3 ] + [Cd 4 (SH) 2 (CH 3 COO) 5 (H 2 S)] + [Cd 4 (SH) 2 (CH 3 COO) 5 ] + [Cd 4 S(SH)(CH 3 COO) 4 ] + [Cd 4 SH(CH 3 COO) 6 (H 2 S)] + 9x10 -9 torr [Cd 4 (SH) 4 (CH 3 COO) 3 ] + [Cd 4 S(SH) 3 (CH 3 COO) 2 ] + [Cd 4 (SH) 3 (CH 3 COO) 4 (H 2 S)] + [Cd 4 S(SH) 4 (CH 3 COO)] + [Cd 4 S(SH) 3 (CH 3 COO) 2 (H 2 S)] + [Cd 4 (CH 3 COO) 7 ] + +H 2 S (g) [Cd 4 SH(CH 3 COO) 6 ] + [Cd 4 (SH) 3 (CH 3 COO) 4 ] + [Cd 4 S(SH) 2 (CH 3 COO) 3 ] + [Cd 4 (SH) 2 (CH 3 COO) 5 (H 2 S)] + [Cd 4 (SH) 2 (CH 3 COO) 5 ] + [Cd 4 S(SH)(CH 3 COO) 4 ] + [Cd 4 SH(CH 3 COO) 6 (H 2 S)] + 9x10 -9 torr [Cd 4 (SH) 4 (CH 3 COO) 3 ] + [Cd 4 S(SH) 3 (CH 3 COO) 2 ] + [Cd 4 (SH) 3 (CH 3 COO) 4 (H 2 S)] + [Cd 4 S(SH) 4 (CH 3 COO)] + [Cd 4 S(SH) 3 (CH 3 COO) 2 (H 2 S)] + Reactant P (10 -9 torr) H (kcal/mol) k 1 /k c k 2 /k c k 3 /k c k 4 /k c k 5 /k c [Cd(CH 3 COO)] Not Obs [Cd 2 (CH 3 COO) 3 ] [Cd 3 (CH 3 COO) 5 ] [Cd 3 (CH 3 COO) 5 ] [Cd 4 (CH 3 COO) 7 ] Cationic Cadmium Clusters [Cd(NO 3 )] Not Obs [Cd(NO 3 )(CH 3 OH)] [Cd(NO 3 )(CH 3 OH)(H 2 O)] [CdCl] Not Obs [CdCl(CH 3 OH)] [CdOH] Not Obs [CdOH(CH 3 OH)] [ZnCl] Not Obs [ZnCl(CH 3 OH)] Reactant P (10 -9 torr) H (kcal/mol) k 1 /k c k 2 /k c k 3 /k c k 4 /k c k 5 /k c [Cd(CH 3 COO)] Not Obs [Cd 2 (CH 3 COO) 3 ] [Cd 3 (CH 3 COO) 5 ] [Cd 3 (CH 3 COO) 5 ] [Cd 4 (CH 3 COO) 7 ] Cationic Cadmium Clusters [Cd(NO 3 )] Not Obs [Cd(NO 3 )(CH 3 OH)] [Cd(NO 3 )(CH 3 OH)(H 2 O)] [CdCl] Not Obs [CdCl(CH 3 OH)] [CdOH] Not Obs [CdOH(CH 3 OH)] [ZnCl] Not Obs [ZnCl(CH 3 OH)] Cationic Metal Clusters show much higher reaction efficiencies. Reactant P (10 -9 torr) H (kcal/mol) k 1 /k c k 2 /k c k 3 /k c k 4 /k c k 5 /k c [Cd(CH 3 COO)] Not Obs [Cd 2 (CH 3 COO) 3 ] [Cd 3 (CH 3 COO) 5 ] [Cd 3 (CH 3 COO) 5 ] [Cd 4 (CH 3 COO) 7 ] Cationic Cadmium Clusters [Cd(NO 3 )] Not Obs [Cd(NO 3 )(CH 3 OH)] [Cd(NO 3 )(CH 3 OH)(H 2 O)] [CdCl] Not Obs [CdCl(CH 3 OH)] [CdOH] Not Obs [CdOH(CH 3 OH)] [ZnCl] Not Obs [ZnCl(CH 3 OH)] Reactant P (10 -9 torr) H (kcal/mol) k 1 /k c k 2 /k c k 3 /k c k 4 /k c k 5 /k c [Cd(CH 3 COO)] Not Obs [Cd 2 (CH 3 COO) 3 ] [Cd 3 (CH 3 COO) 5 ] [Cd 3 (CH 3 COO) 5 ] [Cd 4 (CH 3 COO) 7 ] Cationic Cadmium Clusters [Cd(NO 3 )] Not Obs [Cd(NO 3 )(CH 3 OH)] [Cd(NO 3 )(CH 3 OH)(H 2 O)] [CdCl] Not Obs [CdCl(CH 3 OH)] [CdOH] Not Obs [CdOH(CH 3 OH)] [ZnCl] Not Obs [ZnCl(CH 3 OH)] Reaction rates vary significantly with successive sulfide addition. Reactant P (10 -9 torr) H (kcal/mol) k 1 /k c k 2 /k c k 3 /k c k 4 /k c k 5 /k c [Cd(CH 3 COO)] Not Obs [Cd 2 (CH 3 COO) 3 ] [Cd 3 (CH 3 COO) 5 ] [Cd 3 (CH 3 COO) 5 ] [Cd 4 (CH 3 COO) 7 ] Cationic Cadmium Clusters [Cd(NO 3 )] Not Obs [Cd(NO 3 )(CH 3 OH)] [Cd(NO 3 )(CH 3 OH)(H 2 O)] [CdCl] Not Obs [CdCl(CH 3 OH)] [CdOH] Not Obs [CdOH(CH 3 OH)] [ZnCl] Not Obs [ZnCl(CH 3 OH)] NO 3 > OH > Cl Reactant P (10 -9 torr) H (kcal/mol) k 1 /k c k 2 /k c k 3 /k c k 4 /k c k 5 /k c [Cd(CH 3 COO)] Not Obs [Cd 2 (CH 3 COO) 3 ] [Cd 3 (CH 3 COO) 5 ] [Cd 3 (CH 3 COO) 5 ] [Cd 4 (CH 3 COO) 7 ] Cationic Cadmium Clusters [Cd(NO 3 )] Not Obs [Cd(NO 3 )(CH 3 OH)] [Cd(NO 3 )(CH 3 OH)(H 2 O)] [CdCl] Not Obs [CdCl(CH 3 OH)] [CdOH] Not Obs [CdOH(CH 3 OH)] [ZnCl] Not Obs [ZnCl(CH 3 OH)] Calculated reaction enthalpy is consistent with observed reactivity. Conclusions ESI of salt solutions show variation of cluster size vs. time. Data suggests that both % methanol and concentration play a role. Solution experiments show successive substitutions of mp for NO 3 Treatment with H 2 S leads to replacement of (NO 3 ) 2 with SO 4 for larger clusters. Gas phase ion-molecule reactions between metal salt clusters and H 2 S result in the formation of a variety of metal sulfide species. Cationic clusters display < 5% reaction efficiency with the exception of [Cd 4 (CH 3 COO) 9 ] - Anionic metal clusters show higher initial reaction efficiencies which decreases significantly with successive SH - substitution. DFT calculations are consistent with gas phase reactivity (Kaitlin Papson). Similarities between gas and condensed phases highlighted by salt nucleation in binary solvents, spectator solvent molecules, and similarities in [Cd x (NO 3 ) 2x+1 ] - reactivity. 10 1 Size (nm) Dissolved Ions Clusters Nanoparticles Solid state material Project Goal Mass Spectrometry Spectroscopy The Big Picture Elucidation of initial steps for metal sulfide formation Gas phase ion-molecule reactions as models for aqueous metal sulfide reactions The Next Step: high pressure source-side reactions. Structural characterization Surface deposition Tying it all together. The technique: FT-ICR MS Understanding environmental chemical processes Atmospheric: Biomolecules Aquatic: Inorganic clusters Analytical Chemistry Mass Spectrometry Acknowledgements Dr. Ridge Our Research Group Kaitlin Papson Nick Zeringo Una Kim Scott Robinson Collaborators George Luther Kate Mullaugh Murray Johnston Julie Lloyd Julia Laskin (PNNL) Funding UD GK-12 NSF Delaware EPSCoR UD IGERT Environmental Perspective Evidence of Salt Nucleation at Hydrothermal Sites Salt deposits gyser-like brine discharges salt diapirs ( d pr ) Buoyant/Mobile salt layer piercing the brittle overlying rock Hovland, M.; Rueslatten, H. G.; Johnsen, H. K.; Kvamme, B.; Kuznetsova, T. Salt Formation Associated with Sub-Surface Boiling and Supercritical Water. Mar. Pet. Geol. 2006, 23, Hovland, M.; Fichler, C.; Rueslatten, H.; Johnsen, H. K. Deep-Rooted Piercement Structures in Deep Sedimentary Basins - Manifestations of Supercritical Water Generation at Depth? J. Geochem. Explor. 2006, 89, FT-ICR MS + + B B XX f = qB 2m2m FT-ICR MS + + B XX _ + Why we care? Past Research The Instrument Making Clusters Gas Phase Moving Forward Fourier Transform f = qB 2m2m Energy Resolved FECs: AngII+3O Collision Energy (eV) Relative Intensity Asp-Arg-Val- Tyr(+O) -Ile- His(+3O) -Pro-Phe [AngII+3O]-45 [AngII+3O]-71 Asp-Arg-Val- Tyr(+O) -Ile- His(+3O) -Pro-Phe b5b5 -88 AngII+3O: b 5 fragment [AngII+3O] fragment RRKM Modeling: Dr. Julia Laskin [MH+nO] + DRVYIHPFDRVY * IHPFDRVYIH * PFDRVY * IH * PF M/Z E 0 (eV) S (cal/mol K) Relative E A, s x x x x10 10 Log (A) TST: Arrhenius Equation Survival Curves Frequencies Activation energy Activation Entropy RRKM Energy Deposition Frequencies E 0 & S Electrospray Mechanism Solution Chemistry: Tetranuclear Anions A)3 mM aqueous solution of Cd(NO 3 ) 2 4H 2 O diluted 50/50 with MeOH. B)1.5 mM aqueous solution of Cd(NO 3 ) 2 4H 2 O and 2- mercaptopyridine (1:1) diluted 50/50 with MeOH. C)H 2 S(g) bubbled through a 3 mM aqueous solution of Cd(NO 3 ) 2 4H 2 O followed by addition of 2-mercaptopyridine (1:1), then diluted 50/50 with MeOH. Solution Chemistry: Pentanuclear Anions A)3 mM aqueous solution of Cd(NO 3 ) 2 4H 2 O diluted 50/50 with MeOH. B)1.5 mM aqueous solution of Cd(NO 3 ) 2 4H 2 O and 2- mercaptopyridine (1:1) diluted 50/50 with MeOH. C)H 2 S(g) bubbled through a 3 mM aqueous solution of Cd(NO 3 ) 2 4H 2 O followed by addition of 2-mercaptopyridine (1:1), then diluted 50/50 with MeOH. Bimolecular Rate Constants [Cd(NO 3 )(CH 3 OH)] + k 1 = 2.85 0.27 s -1 Determine [H 2 S] Assume fasted measured k is collision rate limited. Capture Collision Theory 4x10 -9 Torr D dipole moment (0.97 D) ' volume polarizability (3.67 3 ) = 2.49 reduced mass ( Da) Theoretical collision rate Bimolecular Rate Constants [Cd(NO 3 )(CH 3 OH)] + k 1 = 2.85 0.27 s -1 Determine [H 2 S] Assume fasted measured k is collision rate limited. Capture Collision Theory 4x10 -9 Torr Theoretical collision rate [H 2 S] = 2.34x10 9 molecules cm -3 [H 2 S] = 6.62x10 -8 Torr Slowest reaction observed FastestSlowest Reaction Efficiency [Cd(NO 3 )(CH 3 OH)] + Fastest Slowest