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1 Supramolecular Allosteric Cofacial Porphyrin Complexes Christopher G. Oliveri, Nathan C. Gianneschi, SonBinh T. Nguyen,*, Chad A. Mirkin,*, Charlotte L. Stern, Zdzislaw Wawrzak,and Maren Pink J. Am. Chem. Soc. 2007, 128, 16286 - 16296 Speaker

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2 Allosteric Recognition Chad A. Mirkin et. al. Angew. Chem. Int. Ed. 2006, 45, 941 944 The allosteric-effector-mediated shape change of a macrocycle.

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3 Introduction-Porphyrin 93

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4 Chlorophy11 Vitamin B 12

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5 Holliday, B. J. et. al. Angew. Chem. Int. Ed. 2001, 40, 2022-2043. Supramolecular Coordination Chemistry Hydrogen bonding - interaction Metal to ligand binding van der Waals forces

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6 The Directional-Bonding Approach Holliday, B. J. et. al. Angew. Chem. Int. Ed. 2001, 40, 2022-2043.

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7 The Symmetry-Interaction Approach Dinuclear structures Tetranuclear structures The symmetry-interaction synthetic strategy has granted researchers access to a variety of elegant shapes andarchitectures (for example, helicates, tetrahedra, and adamantoidstructures) through the predictable coordination chemistry of multibranched chelating ligands with transition and main group metal centers. Holliday, B. J. et. al. Angew. Chem. Int. Ed. 2001, 40, 2022-2043.

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8 The Weak-Link Approach A critical feature of this approach is that themetals used in the assembly process are available forfurther reactions without destroying the supramolecularstructure. This approach targets condensed structures that contain strategically placed strong(metal-phosphine) and weak (metal-X) bonds. Mirkin, C. A. Acc. Chem. Res. 2005,38,825-837.

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9 Catalytic Acyl Transfer by a Cyclic Porphyrin Trimer Sanders, J. K. M. et. al. J. Am. Chem. Soc. 1994,116, 3141-3142. Tetrahedral intermediate doubly-bound inside cavity of trimer. Schematic view of a proximity-catalyzed transfer reaction.

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10 Design of Allosteric Porphyrin-Based Supramolecules Closed macrocycleOpen macrocycle PPh 2 = diphenylphosphine MES = 1,3,5-trimethylbenzene

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11 ( i ) 1-bromo-2-chloroethane, K 2 CO 3, Acetone, Reflux ( ii) 1,3-propanedithiol, Y(OTf) 3 (5 mol %), CH 3 CN (iii) KPPh 2, THF (iv) S 8, THF ( v) NaNO 2,AcCl/H 2 O, CH 2 Cl 2, 0 C rt 75%86%97% Synthesis of Ether-Based Ligand 7 and Macrocycles 8a and 8b Y(OTf) 3

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12 ( vi ) 5-mesityldipyrromethane, BF 3 OEt 2, DDQ, NEt 3, CHCl 3, 4 Molecular Sieves (vii ) Zn(OAc) 2 2H 2 O, 4:1 CHCl 3 /MeOH, Reflux (viii) Cp 2 ZrHCl, THF, 60 C 88% 41% 96% ( DDQ ) 5-mesityldipyrromethane

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13 (ix) [Rh(CO) 2 (Cl)] 2, CH 2 Cl 2 /THF ( x) [Cu(CH 3 CN) 4 ]PF 6, CH 2 Cl 2 /THF 89% 8a 94% 8b 92%

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14 X-ray crystal structure of 8a DABCO as viewed (A) from the side and (B) from the top Gray C Pink Rh, Red O, Yellow Cl, Green P, Blue N, Light Blue Zn Zn-Zn distance of 7.09 Rh-Rh distance of 24.85 P-Rh-P distance of 4.64 DABCO

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15 X-ray crystal structure of 8c DABCO as viewed (A) from the side and (B) from the top Zn-Zn distance 6.99 Cu-Cu distance 22.6 Gray C Brown Cu, Red O, Yellow Cl, Green P, Blue N, Light Blue Zn

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16 ( i ) ClCH 2 CH 2 PPh 2, Cs 2 CO 3, CH 3 CN, Reflux ( ii) S 8, THF (iii) n-BuLi, DMF, THF, -78 C (iv) 5-mesityldipyrromethane, BF 3 OEt 2, DDQ, NEt 3,CHCl 3, 4 Molecular Sieves 92%88% 44% Synthesis of Thioether-Based Ligand 13 and Macrocycles 14a-b, 15a-b

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17 ( v ) Zn(OAc) 2 2H 2 O, 4:1 CHCl 3 /MeOH, Reflux ( vi ) Cp 2 ZrHCl, THF, 60 C ( vii) for 14a: [Rh(NBD)Cl] 2, AgBF 4, CH 2 Cl 2 /THF (viii) for 14b: [Cu(CH 3 CN) 4 ]PF 6, CH 2 Cl 2 /THF 98%88%

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18 (ix) for 15a: PPNCl/CO (1 atm) ( x) for 15b: C 5 D 5 N. 14a 90% 14b 90% Bis(triphenylphosphoranylidene) ammonium chloride (PPNCl)

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19 NMR Data of 14a and 14b Chad A. Mirkin et. al. Inorg. Chem. 2000, 39, 3432-3433 Comp. 2 31P{1H} NMR (CD2Cl2) 64 ppm (d,J Rh-P =161 Hz) Comp. 14a 31 P{ 1 H} NMR (CD 2 Cl 2 ) 64.5 ppm (d,J Rh-P =162 Hz)

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20 X-ray crystal structure of 15a DABCO as viewed (A) from the side and (B) from the top Gray C Pink Rh, Red O, Orange S, Yellow Cl, Green P, Blue N, Light Blue Zn Zn-Zn distance 7.02 Rh-Rh distance 22.59 P-Rh-P distance 4.60 Dihedral angles 17.8

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21 X-ray crystal structure of 15c DABCO as viewed (A) from the side and (B) from the top Gray C Brown Cu, Red O, Yellow Cl, Green P, Blue N, Light Blue Zn Zn-Zn distance 7.05 Cu-Cu distance 22.38

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22 Closed macrocycleOpen macrocycle Acyl transfer reactions catalyzed by a closed macrocycle vs. the corresponding open macrocycle.

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23 Formation of 4-(acetoxymethyl)pyridine (4-AMP) plotted as concentration vs. time for 14a and 15a.

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24 Formation of 4-(acetoxymethyl)pyridine (4-AMP) plotted as concentration vs. time for [Zn(TPP) + 16a] and [Zn(TPP) + 16b]

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25 Catalytic efficiency of 4-PC 15a 14a = 2 1 15a monomer = 14 1 14a is probably dynamic when in solution and the observed catalytic activity may originate from the conformational flexibility around the S atoms.

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26 Formation of 3-(acetoxymethyl)pyridine (3-AMP) plotted as concentration vs. time for 14a and 15a.

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27 Formation of 3-(acetoxymethyl)pyridine (3-AMP) plotted as concentration vs. time for [Zn(TPP) + 16a] and [Zn(TPP) + 16b]

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28 Catalytic efficiency of 3-PC Drop slightly with respect to 4-PC => the cavities of 14a and 15a are still flexible enough to accommodate the change in transition state distance for acyl transfer from acetylimidazole upon binding.

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29 Formation of 2-(acetoxymethyl)pyridine (2-AMP) plotted as concentration vs. time for 14a and 15a.

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30 Formation of 2-(acetoxymethyl)pyridine (2-AMP) plotted as concentration vs. time for [Zn(TPP) + 16a] and [Zn(TPP) + 16b]

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31 Catalytic efficiency of 2-PC Drop significantly with respect to 3-PC and 4-PC Similar to those observed for the monomer => Unfavorable transition state (in comparison to those for 3-PC and 4-PC) for productive acyl transfer.

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32 Conclusion They have developed a coordination chemistrybased synthetic approach for the quantitative preparation of flexible cofacial porphyrin assemblies in which the porphyrins act as functional sites within an allosteric framework that istunable via modulation of peripheral structure control domains. This capability enables the cofacial porphyrin structuresto act as allosteric catalysts capable of discriminatingdifferent substrate combinations and selectively transformingthem into the desired products.

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33 Table 1. X-ray Crystallographic Data for 8a DABCO and 15a DABCO

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34 Table 1. X-ray Crystallographic Data for 8c DABCO and 15c DABCO.

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35 Homework 1. paper 15a 14b Ans

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36 2. Weak-link approach (WLA) transition metal Ans Transition metal Rh() Pd() 1 macrocycle transition metal d 8 Rh() d 10 Cu() d 6