1. EXPLORING SOLVENT SHAPE AND FUNCTION USING MASS- AND ISOMER-SELECTIVE VIBRATIONAL SPECTROSCOPY Special thanks to Tom, Anne and Terry

2. Outline  Ar-cluster mediated trapping of reaction intermediates as size- selected cluster ions  Reaction motifs in water splitting  Characterization by vibrational predissociation spectroscopy  Network-dependent activation of water in covalent bond formation: NO + · (H 2 O) n  Instrument modifications to access electrosprayed ions  Ring closure mechanics of dodecanoic acid conjugate anions

3. Yale Rachael Relph Mike Kamrath Chris Leavitt Tim Guasco Arron Wolk Krissy Breen Helen Gerardi Prof. Gary Weddle (Fairfield) AFRL Cambridge Dr. A.A. Viggiano Univ. of Pittsburgh Prof. Ken Jordan Dr. Daniel Schofield Ohio State Prof. Anne McCoy Yale Prof. John Tully Dr. Ryan Steele Experiment Theory Eldon Ferguson

4. Rachael Mike Ben, PhD 2010, Now with Schwartz, UCLA Gary Tim KrissyHelen Thursday talks

5. Yale Solar Group-small biomimetic catalysts “Harnessing the power of photosynthesis to make green fuel”

6. Making the O-O bond Very high oxidation states put water in unusual chemical environment Cooperative, complex reaction coordinate! Proton removed and O-O bond forms O V Ir OH IV Ir -H + /-e ˉ ++ O H H -  + O H H

7. Large shifts in excess proton-based vibrations: “Frozen snapshots” of diffuse ir signature of free proton in dilute acids H + (H 2 O) n ∙Ar spectra Spectral signatures of mobile protons Headrick, M. A. Duncan,MAJ, Science, 308, 1765 (2005),

8. N=O + O H H O H H solvated nitric oxidesolvated nitrosonium clusters provide a controlled environment to titrate the extent of proton transfer -e - N=O O H pKa drop solvation in liquid water leads to formation of acid low dielectric allows only partial release of proton oxidation N=O O H H B:B: + Getting started…2009 Proton-coupled covalent bond formation proton transfer H + O H H

9. NO + (H 2 O) n ∙ Ar p + H 2 O → NO + (H 2 O) n+1 ∙ Ar q + (p-q) Ar Cryogenic Ion Chemistry Rational preparation of reaction intermediates using Ar cluster-mediated condensation NO + (H 2 O) n H2OH2O HONO + H + (H 2 O) n NO + (H 2 O) n + H 2 O → HONO + H + (H 2 O) n Atmo reaction, Ferguson ‘71 Okumura, ‘93 Reaction coordinate is solvent shape 

10. Application to the nitrosonium hydrates 1 keV electron beam NO + ∙ Ar m + H 2 O → NO + (H 2 O) ∙ Ar p + (m-p) Ar NO + (H 2 O) ∙ Ar p + H 2 O → NO + (H 2 O) 2 ∙ Ar q + (p-q) Ar H2OH2O kV NO/Ar time of flight NO + (H 2 O) 2 Ar NO + (H 2 O) 4 Ar NO + (H 2 O) 3 Ar Ar 12 + NO + Ar 9

11. 1 keV electron beam T.O.F. Nd:YAG pumped OPO/OPA 600 – 4500 cm -1 reflectron MCP detector H2OH2O kV NO/Ar NO + (H 2 O) n ∙ Ar p + h  → NO + (H 2 O) n ∙ Ar q + (p-q) Ar Structural characterization by Ar tagged ir spectra

12. increasing charge on solute 1400180022002600300034003800 Photon Energy, cm -1 NO + HONO Distinct spectral regions for solute and solvent response Solute response ReactantProduct H9O4+H9O4+ Free OH increasing charge on solvent Reactant Solvent response Product NO + (H 2 O) n + H 2 O → HONO + H + (H 2 O) n

13. increasing charge on solute 1400180022002600300034003800 Photon Energy, cm -1 H9O4+H9O4+ NO + Predissociation Yield bend Free OH HONO increasing charge on solvent NO + · (H 2 O) 1 NO + · (H 2 O) 2    NO + · (H 2 O) 3 HONO NO + · (H 2 O) 4 Reaction complete Isomers?

14. Argon-solvated Isomer I Argon-solvated Isomer II Isomer I or II fragment induced by pump laser Isomer II fragment induced by probe laser Signal Time of Flight, ms ion beam pulsed valve 1 keV electron gun reflectron h pump h probe coaxial TOF drift tube MCP ion detector MCP ion detector reflectron Nd:YAG pumped OPO/OPA 600 – 4500 cm -1 ±1.5 keV Nd:YAG pumped OPO/OPA 600 – 4500 cm -1 Isomer-selective Spectroscopy: Development of MS 3 IR 2 technique in 2008

15. 19002100    2300 Disentangle high energy bands in DR scanning mode 26003000340038004200 Predissociation Yield Photon Energy, cm -1 Probe  Probe 

16. 3640368037203760 Ion Dip Signal Photon Energy, cm -1 2600300034003800 36003800 Predissociation Yield 24002800320036004000 probe * probe ‡  ‡ A few bands still hopelessly overlapped! Deconvolute using covariance behavior

17. 19002100    2300 Three embedded patterns 26003000340038004200 Predissociation Yield Photon Energy, cm -1 Probe 

18. Calculated isomers of NO + · (H 2 O) 3  E=2.4 (1.9)  E=0.0 (0.0)  E=4.3 (4.0)  E=2.6 (2.2)  E=3.4 (1.2) MP2/aug ‑ cc ‑ pVTZ kcal/mol (ZPE corrected) Three observed by hole burning

19. increasing charge on solute 1400180022002600300034003800 Photon Energy, cm -1 H9O4+H9O4+ NO +  Predissociation Yield bend Free OH  HONO  increasing charge on solvent 3-  3-  3-  Strong correlation between solvent and solute response to changing solvent coordinate

20. Arrangement stabilizes charge on shared protons γ motif with two waters in second solvation shell most reactive + Hydrated NO + Electron flow O H N H O

21. 3-  3-  3-  Intra-cluster charge-transfer (neutralization of NO + ) strongly dependent on shape of attached water network Electron density difference contours upon ion hydration (fixed water network at product geometry) Explicit, molecular level solvent coordinate for reaction Relph et al., Science, January 2010

22. parent ion 800700600500400300 Mass (amu) mass = 483 “Cryogenic ion chemistry” with water splitting catalysts?

23. Cryogenic Ion Chemistry Rational preparation of reaction intermediates using Ar cluster-mediated condensation

24. Standard approach: Ar tagging in supersonic expansion –Argon Heat of Evaporation: 500 cm -1 –Only works on small systems where vibrational degrees of freedom can be quenched by Ar during the expansion Challenge: Vibrational cooling of large systems X·Ar n X·Ar m + Ar n-m NO + · (H 2 O) 3 · 7 ArNO + · (H 2 O) 3 · Ar + 6 Ar 3N – 6 = 27 ~ 9 Ar atoms 3N – 6 = 135 ~ 50 Ar atoms

25. Tagging with H 2 Xuebin Wang at PNNL {ONLY the dianions tag with H 2 } Thank You Lai-Sheng Wang and Xuebin Wang! - O 2 C(CH 2 ) 12 CO 2 -  n H 2

26. RF only quadrupoles Heated copper block 1 st skimmer 2 nd skimmer aperture Octopole ion guide 90° quadrupole ion bender H 2 /He filled 3-D quadrupole ion trap with temerature control to 8 K Octopole ion guide with Einzel stack Electrospray needle Instrument construction 2009-2010 Thanks: Tom Rizzo Scott Anderson Dieter Gerlich Xuebin and Lai-Sheng

27. He/H2 buffer gas 72747678 Time of Flight (ms) 30 ms 50 ms 40 ms 20 ms 0 ms doubly-charged parent RF Pulsed valve Ions in Ions out Paul Trap H 2 adduct formation in a 3-D Paul trap: Pulse cooling gas and delay extraction after pump out 10 ms gas pulse Delay to extraction 10 K

28. Starting with a known standard – O 2 C(CH 2 ) 6 CO 2 – · Kr

29. 1200160020002800320036004000 CO 2 sym. stretch H 2 predissociation spectroscopy Okumura & Lee 1990 Photon Energy, cm -1 H 2 stretch B3LYP/6-311++g(d,p) Calculated Intensity H 2 Prediss. Yield – O 2 C(CH 2 ) 10 CO 2 – · (H 2 ) 10 + hν → – O 2 C(CH 2 ) 10 CO 2 – · (H 2 ) 5 + 5 H 2 CH stretches Dodecanedioic acid O OH O HO C-O stretches

30. H 2 attachment site 1200160020002800320036004000 Photon Energy, cm -1 H 2 Prediss. Yield Calculated Intensity B3LYP/6-311++g(d,p) CH stretches H 2 stretch CO 2 sym. stretch Free H 2 CO 2 asym. stretch

31. Packing of H 2 molecules n = 10 Relatively sharp, red-shifted band (by 250 cm -1 ) Many molecules in first solvent shell? B3LYP/6-311++G(d,p) Can fit 8 H 2 around each CO 2 group

32. Where the H 2 sticks in the di-anion 1200160020002800320036004000 Photon Energy, cm -1 H 2 Prediss. Yield Calculated Intensity B3LYP/6-311++g(d,p) H 2 stretch CO 2 asym. stretch CO 2 sym. stretch CH stretches

33. Where the H 2 sticks in the di-anion 1200160020002800320036004000 Photon Energy, cm -1 H 2 Prediss. Yield Calculated Intensity B3LYP/6-311++g(d,p) H 2 stretch CO 2 asym. stretch CO 2 sym. stretch CH stretches

34. Extending H 2 tagging to the singly-charged species [CO 2 (CH 2 ) 10 CO 2 H] - · nH 2 T=11 K 224226228230232234236238240 m/z n =01234 72747678 Time of Flight (ms) n = 14 many peaks but only doubly-charged species tags

35. 100014001800220026003000340038004200 Predissociation Yield Photon Energy, cm -1 Calculated Intensity a) b) c) free H 2 stretch free OH shared proton CH stretches C=O stretches CH backbone Missing free OH signals ring formation

36. C-O bands reveal asymmetrical internal H-bond C=O Blue shift C-O red shift CO 2 ˉ bond order 1.5

37. 8001200160020002800320036004000 Photon Energy, cm -1 C-O bands reveal asymmetrical internal H-bond Carboxylate is intact

38. 8001200160020002800320036004000 Photon Energy, cm -1 C-O bands reveal asymmetrical internal H-bond Carbonyl emerges

39. 8001200160020002800320036004000 Photon Energy, cm -1 C-O bands reveal asymmetrical internal H-bond C-OH lost in CH 2 background

40. Going to need a better mass spec Current mass spec only has unit mass resolution at 500 AMU Photocatalysts have metal centers with multiple isotopes ex: 191 Ir (37%) and 193 Ir (63%) With doubly charged species loss of a single H 2 may be difficult to detect

41. The next generation: ICR Delivery date: June 7 Etienne Garand, PhD Neumark Delivery date: July 1. Resolution 450,000 16 cm bore (77 K cell, Williams, Berkeley)

42. Observed explicit solvent coordinates facilitating covalent N-O bond formation Implemented cryogenic ion source into triple-focusing tof mass spec to study photoactive catalysts from the Yale Solar Group Next phase of construction: ICR Conclusions Thank you