New cation-‘capped’ complex of the Z-isomer of a crown-containing styryl dye bearing a long N-ammonioalkyl substituent

Molecular self-assembly is an effective strategy for controlling the [2 + 2] photocycloaddition reaction of olefins. The geometrical properties of supramolecular assemblies are proven to have a critical effect on the efficiency and selectivity of this photoreaction both in the solid state and in solution, but the role of other factors remains poorly understood. Convenient supramolecular systems to study the structure-property relationships are pseudocyclic dimers spontaneously formed by styryl dyes containing a crown ether moiety and a remote ammonium group. New dyes of this type were synthesized to investigate the effects of structural and electronic factors on the quantitative characteristics of supramolecular dimerization and [2 + 2] photocycloaddition in solution. Variable structural parameters for the styryl dyes were the size and structure of macrocyclic moiety, the nature of heteroaromatic residue, and the length of the ammonioalkyl group attached to this residue. Quantum chemical calculations of the pseudocyclic dimers were performed in order to interpret the relationships between the structure of the ammonium dyes and the efficiency of the supramolecular photoreaction. One of the dimeric complexes was obtained in the crystalline state and studied by X-ray diffraction. The results obtained demonstrate that the photocycloaddition in the pseudocyclic dimers can be dramatically affected by the electronic structure of the styryl moieties, as dependent on the electron-donating ability of the substituents on the benzene ring, and by the conformational flexibility of the pseudocycle, which determines the mobility of the olefinic bonds. The significance of electronic factors is highlighted by the fact that the photocycloaddition quantum yield in geometrically similar dimeric structures varies from ≤10(-4) to 0.38. The latter value is unusually high for olefins in solution.

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“… a MeCN- d 3 , 25 ± 1 °C; the equilibrium constants are measured to within about 30%. b Reference . c Reference . …”

Section: Results and Discussionmentioning

confidence: 99%

“…Compounds 1 – 3 , , 4b , 6b , 7a,b , and 9 were obtained according to published procedures. Dyes 4a , 5a,b , and 6a were synthesized as shown in Scheme .…”

Section: Experimental Sectionmentioning

confidence: 99%

Supramolecular Dimerization and [2 + 2] Photocycloaddition Reactions of Crown Ether Styryl Dyes Containing a Tethered Ammonium Group: Structure–Property Relationships

et al. 2015

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“…The chromophore of dye 1f is planar, which is confirmed by the dihedral angle of 5.41 between the pyridine and benzene ring planes. The ethylene bond is also rather localized: the distances in the C(6)-C( 9)QC(10)-C(11) moiety are 1.469 (7), 1.324 (7), and 1.465( 7) Å, respectively. The ammoniopropyl N-substituent has a trans, gauche conformation, although the steric and Coulomb interactions require that this substituent be in all-transoid conformation.…”

Section: X-ray Diffraction Study Of Dyes and Complexesmentioning

confidence: 99%

“…There are only a few examples of using photoactive 18-crown-6-substituted unsaturated compounds in selfassembly involving the RNH 3 + ions; 6 they were mainly reported by our research group. 5c,d Previously, we demonstrated 7 that the E isomer of a 18-crown-6containing 2-benzothiazole styryl dye having a long ammoniohexyl spacer in the heterocyclic residue, in a MeCN solution, spontaneously forms stable dimeric complexes (log K d = 6.1 [M À1 ]) with the anti-head-to-tail arrangement of chromophores. Upon exposure to light, this dye is converted almost completely to a cationcapped Z isomer stabilized by intramolecular coordination of the ammonium group to the crown ether moiety (Chart 1a).…”

Section: Introductionmentioning

confidence: 99%

Synthesis, structure, and stereospecific cross-[2+2] photocycloaddition of pseudodimeric complexes based on ammonioalkyl derivatives of styryl dyes

et al. 2016

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“…Alternatively, on exposure to light, the formation of a relatively stable cation "capped" complex occurs in the Z form of a dye with intramolecular coordination of the ammonium group by the crown ether fragment. 9 The above mentioned phototransformations result in consid erable hypsochromic shifts in the absorption spectra of the unsaturated compounds, which can be used for the design of the systems for optical recording of information.…”

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confidence: 99%

Stereospecific [2+2] photocycloaddition in a pseudodimeric complex between N-ammoniopropylstyrylpyridine and 18-crown-6-containing styrylpyridine

et al. 2009

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A quaternary 4 styrylpyridinium salt having the N ammoniopropyl substituent forms a pseudodimeric head to tail complex with neutral 18 crown 6 containing 4 styrylpyridine in MeCN through H bonding. This complex undergoes stereospecific [2+2] photocycloaddition due to preorganization of the ethylene bonds in the syn arranged chromophoric fragments of the components. The structure of the rctt isomer of the cyclobutane derivative obtained was established by NMR spectroscopy and X ray diffraction analysis.The self assembly of organic and bioorganic molecules into supramolecular assemblies in solutions through rela tive weak H bonds is widely known. 1,2 At the same time, the self assembly of the photosensitive compounds in volving hydrogen bonding is poorly studied, while it is of great interest due to possible photochemical reactions within the supramolecular assemblies formed that are not observed under other conditions. Crown containing un saturated compounds undergo self assembly in the pres ence of different cations. 3 These photosensitive compounds containing the C=C bond are subject to E-Z isomeriza tion, electrocyclization, and [2+2] photocycloaddition (PCA). We suggested that a versatile approach to the self assembly of crown containing unsaturated compounds can make use of the primary ammonium groups incor porated into the unsaturated compound itself or a photo insensitive substrate. Such type of self assembly may be illustrated by the example of the following supramolecu lar structures. Bis(18 crown 6)stilbene forms extremely stable donor-acceptor complexes with the N,N´ di(am monioalkyl) derivatives of viologen analogs that can serve as fluorescent molecular sensors for the alkaline earth metal cations. 4,5 18 Crown 6 containing bis styryl dyes behave as selective optical molecular sensors for diam monioalkane ions; 6 the stereospecific intramolecular PCA reaction can proceed in the pseudosandwich head to head complexes of dyes that formed to afford a single isomer of a cyclobutane derivative. 7 Due to the H bond ing between the ammonium groups and the crown ether fragments, the crown containing styryl dyes having the N ammonioalkyl substituent in the heterocyclic residue form stable head to tail dimeric complexes wherein efficient stereospecific autophotocycloaddition 8 occurs. Alternatively, on exposure to light, the formation of a relatively stable cation "capped" complex occurs in the Z form of a dye with intramolecular coordination of the ammonium group by the crown ether fragment. 9 The above mentioned phototransformations result in consid erable hypsochromic shifts in the absorption spectra of the unsaturated compounds, which can be used for the design of the systems for optical recording of information.Recently, we have shown 10 that two yellow styryl dyes of the 4 pyridyl series, one of which contained the N ammoniopropyl substituent ((E) 1) and the second one contained the fragment of 18 crown 6 ((E) 2), formed a sufficiently stable pseudodimeric complex (logK = 3.52) in MeCN. Due to cooperative ...

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New cation-‘capped’ complex of the Z-isomer of a crown-containing styryl dye bearing a long N-ammonioalkyl substituent

Cited by 9 publications

References 8 publications

Supramolecular Dimerization and [2 + 2] Photocycloaddition Reactions of Crown Ether Styryl Dyes Containing a Tethered Ammonium Group: Structure–Property Relationships

Supramolecular Dimerization and [2 + 2] Photocycloaddition Reactions of Crown Ether Styryl Dyes Containing a Tethered Ammonium Group: Structure–Property Relationships

Synthesis, structure, and stereospecific cross-[2+2] photocycloaddition of pseudodimeric complexes based on ammonioalkyl derivatives of styryl dyes

Stereospecific [2+2] photocycloaddition in a pseudodimeric complex between N-ammoniopropylstyrylpyridine and 18-crown-6-containing styrylpyridine

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