Molecular Recognition of Carbohydrates by Zinc Porphyrins: Lewis Acid/Lewis Base Combinations as a Dominant Factor for Their Selectivity
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- 作者：Tadashi Mizutani ; Takuya Kurahashi ; Takeshi Murakami ; Noriyoshi Matsumi ; and Hisanobu Ogoshi
- 刊名：Journal of the American Chemical Society
- 出版年：1997
- 出版时间：September 24, 1997
- 年：1997
- 卷：119
- 期：38
- 页码：8991 - 9001
- 全文大小：437K
- 年卷期：v.119,no.38(September 24, 1997)
- ISSN：1520-5126
文摘
A systematic study of the binding of carbohydrates byfunctionalized zinc porphyrins indicated that [5,15-bis(8-quinolyl)porphyrinato]zinc(II)(1) showed marked affinity for octyl glucoside and mannosidein CHCl3(-
G
= 4.5-6.3 kcalmol-1). Analysis of thecomplexation-induced shifts of the carbohydrate OH protons inthe1H NMR revealed that receptor 1 bound the 4-OHgroup of mannoside and glucoside by coordination to the zincandthe 6-OH and 3-OH groups by hydrogen bonding to the quinolyl nitrogenatoms. These NMR results and comparisonof binding affinity with reference receptors and ligands indicated thatreceptor 1 recognized thetrans,trans-1,2-dihydroxy-3-(hydroxymethyl) moiety of carbohydrates by the combinationof Lewis acid (zinc) and Lewis bases(quinolyl nitrogens). Poor affinities of 1 to octylgalactosides and octyl 2-O-methyl-
-mannoside wereascribed toneighboring group effects, where a neighboring group in ligands notdirectly involved in the receptor-ligandinteractions had considerable influence on the affinity throughdestabilizing the hydrogen-bonding-network(s) in thereceptor-ligand complex. The circular dichroism induced in theporphyrin Soret band by complexation with thecarbohydrates displayed characteristic patterns, which parallel thepatterns of the complexation-induced shifts in the1H NMR. The CD patterns sensitively reflected thereceptor-ligand interaction modes, particularly ligandorientationand fluctuation in the complex. Variable-temperature CD revealedthat glucoside was fluctuating on 1 whilemannosidewas rigidly fixed on 1 at room temperature. Addition ofalcohols to CHCl3 suppressed the binding by 1,whileaddition of polar additives such as water, alcohols, phenols, andethers assisted the binding by 3 and 4(-G =0.2-0.4 kcal mol-1) in a low concentrationrange (0-1.5 mol %).
G = 4.5-6.3 kcalmol-1). Analysis of thecomplexation-induced shifts of the carbohydrate OH protons inthe1H NMR revealed that receptor 1 bound the 4-OHgroup of mannoside and glucoside by coordination to the zincandthe 6-OH and 3-OH groups by hydrogen bonding to the quinolyl nitrogenatoms. These NMR results and comparisonof binding affinity with reference receptors and ligands indicated thatreceptor 1 recognized thetrans,trans-1,2-dihydroxy-3-(hydroxymethyl) moiety of carbohydrates by the combinationof Lewis acid (zinc) and Lewis bases(quinolyl nitrogens). Poor affinities of 1 to octylgalactosides and octyl 2-O-methyl--mannoside wereascribed toneighboring group effects, where a neighboring group in ligands notdirectly involved in the receptor-ligandinteractions had considerable influence on the affinity throughdestabilizing the hydrogen-bonding-network(s) in thereceptor-ligand complex. The circular dichroism induced in theporphyrin Soret band by complexation with thecarbohydrates displayed characteristic patterns, which parallel thepatterns of the complexation-induced shifts in the1H NMR. The CD patterns sensitively reflected thereceptor-ligand interaction modes, particularly ligandorientationand fluctuation in the complex. Variable-temperature CD revealedthat glucoside was fluctuating on 1 whilemannosidewas rigidly fixed on 1 at room temperature. Addition ofalcohols to CHCl3 suppressed the binding by 1,whileaddition of polar additives such as water, alcohols, phenols, andethers assisted the binding by 3 and 4(-G =0.2-0.4 kcal mol-1) in a low concentrationrange (0-1.5 mol %).