1 Supramolecular Allosteric Cofacial Porphyrin Complexes Christopher G. Oliveri, Nathan C....
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- Slide 1
- 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
- Slide 2
- 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.
- Slide 3
- 3 Introduction-Porphyrin 93
- Slide 4
- 4 Chlorophy11 Vitamin B 12
- Slide 5
- 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
- Slide 6
- 6 The Directional-Bonding Approach Holliday, B. J. et. al.
Angew. Chem. Int. Ed. 2001, 40, 2022-2043.
- Slide 7
- 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.
- Slide 8
- 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.
- Slide 9
- 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.
- Slide 10
- 10 Design of Allosteric Porphyrin-Based Supramolecules Closed
macrocycleOpen macrocycle PPh 2 = diphenylphosphine MES =
1,3,5-trimethylbenzene
- Slide 11
- 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
- Slide 12
- 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
- Slide 13
- 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%
- Slide 14
- 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
- Slide 15
- 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
- Slide 16
- 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
- Slide 17
- 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%
- Slide 18
- 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)
- Slide 19
- 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)
- Slide 20
- 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
- Slide 21
- 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
- Slide 22
- 22 Closed macrocycleOpen macrocycle Acyl transfer reactions
catalyzed by a closed macrocycle vs. the corresponding open
macrocycle.
- Slide 23
- 23 Formation of 4-(acetoxymethyl)pyridine (4-AMP) plotted as
concentration vs. time for 14a and 15a.
- Slide 24
- 24 Formation of 4-(acetoxymethyl)pyridine (4-AMP) plotted as
concentration vs. time for [Zn(TPP) + 16a] and [Zn(TPP) + 16b]
- Slide 25
- 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.
- Slide 26
- 26 Formation of 3-(acetoxymethyl)pyridine (3-AMP) plotted as
concentration vs. time for 14a and 15a.
- Slide 27
- 27 Formation of 3-(acetoxymethyl)pyridine (3-AMP) plotted as
concentration vs. time for [Zn(TPP) + 16a] and [Zn(TPP) + 16b]
- Slide 28
- 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.
- Slide 29
- 29 Formation of 2-(acetoxymethyl)pyridine (2-AMP) plotted as
concentration vs. time for 14a and 15a.
- Slide 30
- 30 Formation of 2-(acetoxymethyl)pyridine (2-AMP) plotted as
concentration vs. time for [Zn(TPP) + 16a] and [Zn(TPP) + 16b]
- Slide 31
- 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.
- Slide 32
- 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.
- Slide 33
- 33 Table 1. X-ray Crystallographic Data for 8a DABCO and 15a
DABCO
- Slide 34
- 34 Table 1. X-ray Crystallographic Data for 8c DABCO and 15c
DABCO.
- Slide 35
- 35 Homework 1. paper 15a 14b Ans
- Slide 36
- 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