Interaction Between Terminal Zinc–Porphyrins in a U‐Shaped Trimeric Porphyrin Array Bearing Chiral Amino Acid Tails

Arai, T.; Takei, Kiyoshi; Nishino, Norikazu

doi:10.1002/ejoc.200500183

Cited by 4 publications

(1 citation statement)

References 43 publications

(36 reference statements)

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“…Another inconsistency was that if δ value at 8.81 was designated as three β protons of 3 , the area ratio ( δ value larger/ δ value smaller) of the residual five β protons should be 3/2 (in theory), but the actual ratio is 3/6. The δ value of the phenyl proton is larger than the one of the β proton in the porphyrin matrix can also be seen in the work done by Arai et al 19. In particular, the increasing the area of the signal centered at δ = 8.81 ppm (the area of 3 is three times of that of 1 ) implied that the nitration positions of 1 and 3 are the same.…”

Section: Resultssupporting

confidence: 59%

Regiospecific naphthyl nitration of 5,10,15,20‐tetranaphthylporphyrin

Raabe

Yang

et al. 2010

J of Physical Organic Chem

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The nitration reaction of 5,10,15,20-tetranaphthylporphyrin (TNP) was investigated in detail and the mono-, di-, and tri-nitro-TNPs were synthesized in high yield using 65% HNO 3 . The 1 H-NMR study shows that the preferred site of nitration of the naphthyl substituted porphyrin is the carbon atom of the meso-substituents para to its bond to the porphyrin ring. The reaction leads to exquisite regioselectivity in favor of the mono, di, and tri-nitro-TNP. Quantumchemical ab initio calculations at different levels of theory were performed in order to explain the experimentally observed reactivity. RESULTS AND DISCUSSION Selective nitration of TNPCompared to the conventional nitration using fuming nitric acid [12] or NaNO 2 /TFA, [14] the reactions presented in this study proceeded smoothly at room temperature, under mild conditions with easy work-up procedures. Thus, after 0.7 mL 65% HNO 3 (yellow) was added to TNP (0.2 g) in 30 mL of CHCl 3 for about 20 min (monitored at intervals by TLC), 1 was obtained in high yield of 92%. General procedures for the synthesis of 2a, 2b, and 3 were exactly the same as that for 1 except that the reaction time was extended to 40 and 180 min, respectively. MS and TLC (wileyonlinelibrary.com)

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Section: Resultssupporting

confidence: 59%

Regiospecific naphthyl nitration of 5,10,15,20‐tetranaphthylporphyrin

Raabe

Yang

et al. 2010

J of Physical Organic Chem

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Complexation of Chiral Zinc(II)Porphyrin Tweezer with Chiral Guests: Control, Discrimination and Rationalization of Supramolecular Chirality

2020

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A series of 1:1 sandwich complexes consisting of chiral zinc(II) bisporphyrin hosts and a series of chiral guests has been synthesized and has rationalized the underpinning mechanism of chirality transfer in the host−guest supramolecular assemblies. The number of stereogenic centers is also varied in both the host and guests, which provides insight into the overall helicity of the assembly. The interactions between the chiral host and chiral guests have been investigated by UV− visible, CD, and 1 H NMR spectroscopic titrations along with extensive DFT studies. Interestingly, CD spectral changes are very different between chiral guests with one and two chiral centers. It has been observed that the sign of the CD couplet of the host−guest complexes is dictated by the chirality of the host only with guests having one chiral center. The match and mismatch of the chirality of the guest only affects the amplitude of the CD signal; the sign, however, remains intact. In sharp contrast, the helicity of the 1:1 sandwich complex is dictated by the chirality of the guests having two chiral centers. However, amplification of the CD couplet is observed upon matching of the chirality between the host and guest, while a mismatch leads to an inversion of the CD couplet. The enantiomeric host also displays similar trends with chiral guests but with opposite sign. The enantioselective host also displays excellent chiral discrimination ability toward enantiomeric guests with two chiral centers. The guest with the same chirality as the host binds much stronger as compared to its enantiomer. Remarkable enantiodiscrimination effects were also detected in the 1 H NMR spectra of the diastereomeric complexes in which well-resolved separation of the signals is clearly visible. The theoretical calculations are consistent with those of the experiment.

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Acidification and Assembly of Porphyrin at an Interface: Counterion Matching, Selectivity, and Supramolecular Chirality

Zhang

Chen

et al. 2009

ACS Appl. Mater. Interfaces

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The interfacial diprotonation and assemblies of a free-base achiral porphyrin, 5,10,15,20-tetrakis(3,5-dimethoxyphenyl)-21H,23H-porphine, on various acidic subphases were investigated. It has been shown that the compound could be diprotonated in situ on an acidic subphase and can form assemblies. The interfacially organized supramolecular assemblies were transferred onto a solid substrate, and the assemblies showed supramolecular chirality. Interestingly, the supramolecular chirality of the assemblies of the diprotonated species showed a counterion-dependent behavior. For the assemblies fabricated from the aqueous HCl subphases, a strong Cotton effect (CE) could be observed, although the porphyrin itself is achiral. When an aqueous HBr solution was used as the subphase, the assemblies showed a weak CE, whereas no CE could be detected for the assemblies formulated from the HNO3 or HI subphase. Interestingly, when a mixture of HBr and NaCl, or HNO3 and NaCl, was employed as the subphase, the formed assemblies displayed chiral features similar to those fabricated on the HCl subphase, suggesting that the Cl(-) could be preferentially visualized in terms of supramolecular chirality, although the system itself is composed of achiral species. On the basis of the experimental facts and a theoretical calculation, an explanation with regard to the different sizes of the counterions and the distinct binding affinities of the counteranions to the diprotonated porphyrin species has been proposed. Our findings provide new insights into the assembly of the diprotonated porphyrins as well as the interfacially occurring symmetry breaking.

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Interaction Between Terminal Zinc–Porphyrins in a U‐Shaped Trimeric Porphyrin Array Bearing Chiral Amino Acid Tails

Cited by 4 publications

References 43 publications

Regiospecific naphthyl nitration of 5,10,15,20‐tetranaphthylporphyrin

Regiospecific naphthyl nitration of 5,10,15,20‐tetranaphthylporphyrin

Complexation of Chiral Zinc(II)Porphyrin Tweezer with Chiral Guests: Control, Discrimination and Rationalization of Supramolecular Chirality

Acidification and Assembly of Porphyrin at an Interface: Counterion Matching, Selectivity, and Supramolecular Chirality

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