Hierarchical organization of a robust porphyrin cage self-assembled by hydrogen bonds

Singh, Sunaina; Aggarwal, Amit; Farley, Christopher; Hageman, Brian; Batteas, James D.; Drain, Charles Michael

doi:10.1039/c1cc11553g

Cited by 16 publications

(9 citation statements)

References 32 publications

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“…Besides their exceptional optical, photophysical and electrochemical properties extensively exploited for decades in donor-acceptor systems [1] and molecular photovoltaics, [2][3][4] porphyrins (Pors) have also proved to be extraordinary supramolecular scaffolds in the design of sophisticated 1D-, 2D-and 3D-dimensional architectures, [5][6][7][8][9] covalently or self-assembled, [10][11][12][13][14] including chiral materials [15][16][17] or sensors, [18] molecular cages, [19][20][21][22][23] turnstiles, [24] tweezers [25,26] and dendrimer cores. [9] Since the first reported example in 1969, [27] atropisomerism in porphyrins has been a concept widely exploited in these kinds of architectures (and, in particular, in tetra-meso-arylporphyrins).…”

Section: Introductionmentioning

confidence: 99%

Tautomerism and Atropisomerism in Free‐Base (meso)‐Strapped Porphyrins: Static and Dynamic Aspects

Urbani

Torres

2014

Chemistry A European J

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We report herein some outstanding examples of atropisomerism and tautomerism in five (meso-)strapped porphyrins. Porphyrins S0-S4 have been synthesised, characterised and studied in detail by spectroscopic and spectrometric techniques, and their isomeric purity verified by HPLC analysis. In particular, they exhibit perfectly well-defined NMR spectra that display distinct patterns depending on their average symmetry at room temperature: C2v , D2d , C2h , C2v , and D2h for S0-S4, respectively. NH tautomerism was evidenced by variable-low-temperature (1) H NMR experiments in [D2 ]dichloromethane performed on S0 (Δ${G{{{\ne}\hfill \atop {\rm 298K}\hfill}}}$=48±1 kJ mol(-1) ) and S1 (Δ${G{{{\ne}\hfill \atop {\rm 298K}\hfill}}}$=55±3 kJ mol(-1) ), which has led to an understanding of the average spectra observed for the five porphyrins at room temperature. On the other hand, S2 and S3 are stable atropisomers at room temperature, easily separated and characterised, as a result of restricted rotation of their strapped bridges due to their high rotational barrier energies. Upon heating to 82 °C, they slowly equilibrate to a thermodynamic ratio of 64:36 in favour of the more stable S2 isomer. This atropisomerisation process was evidenced by (1) H NMR spectroscopy and monitored by HPLC, from which high rotational energy barriers of 115.2 (Δ${G{{{\ne}\hfill \atop {\rm S2}\rightarrow {\rm S3}\hfill}}}$) and 116.9 kJ mol(-1) (Δ${G{{{\ne}\hfill \atop {\rm S2}\rightarrow {\rm S3}\hfill}}}$) were deduced.

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Section: Introductionmentioning

confidence: 99%

Tautomerism and Atropisomerism in Free‐Base (meso)‐Strapped Porphyrins: Static and Dynamic Aspects

Urbani

Torres

2014

Chemistry A European J

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“…4 Hydrogen bonding is an example of highlydirectional intermolecular force that is known to control supramolecular structure in a variety of self-assembled systems, including porphyrin aggregates. [20][21][22] The present work employs isotopic substitution to explore the possible role of hydrogen bonding in the TSPP aggregate.…”

Section: Introductionmentioning

confidence: 99%

Influence of hydrogen bonding on excitonic coupling and hierarchal structure of a light-harvesting porphyrin aggregate

Rich

McHale

2012

Phys. Chem. Chem. Phys.

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Helical porphyrin nanotubes of tetrakis(4-sulfonatophenyl)porphyrin (TSPP) were examined in DCl/D(2)O solution using resonance Raman and resonance light scattering spectroscopy to probe the influence of hydrogen bonding on the excitonic states. Atomic force microscopy reveals similar morphology for aggregates deposited from DCl/D(2)O and from HCl/H(2)O solution. Deuteration results in subtle changes to the aggregate absorption spectrum but large changes in the relative intensities of Raman modes in the J-band excited resonance Raman spectra, revealing relatively more reorganization along lower-frequency vibrational modes in the protiated aggregate. Depolarization ratio dispersion and changes in the relative Raman intensities for excitation wavelengths spanning the J-band demonstrate interference from overlapping excitonic transitions. Distinctly different Raman excitation profiles for the protiated and deuterated aggregates reveal that isotopic substitution influences the excitonic structure of the J-band. The deuterated aggregate exhibits a nearly two-fold increase in intensity of resonance light scattering as a result of an increase in the coherence number, attributed to decreased exciton-phonon scattering. We propose that strongly coupled cyclic N-mers, roughly independent of isotopic substitution, largely decide the optical absorption spectrum, while water-mediated hydrogen bonding influences the further coherent coupling among them when they are assembled into nanotubes. The results show that, similar to natural light-harvesting complexes such as chlorosomes, hydrogen bonding can have a critical influence on exciton dynamics.

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“…Ordered supramolecular arrays of various porphyrin derivatives are built by utilizing weak interactions. [94][95][96][97][98][99][100][101][102] In a pre-organized environment, there is no scope for solvent reorganization hence primary electron reactions are fast even at very low temperature. Non-covalent self-assemblies have orderly arranged porphyrin units.…”

Section: Assemblies Of Chelated and Macrocyclic Ligand Complexesmentioning

confidence: 99%

“…105 The complex 18 has uracil groups attached to the periphery of porphyrin rings; these participate in hydrogen bonds with bis(decyl)melamine (19) to form cage-like architecture. 100 The hydrogen bonds between the host and guest is shown in Figure 11. Self-assembly of the porphyrin cages organizes as film of nano-meter thickness on mica surface.…”

Section: Assemblies Of Chelated and Macrocyclic Ligand Complexesmentioning

confidence: 99%

Predominantly ligand guided non-covalently linked assemblies of inorganic complexes and guest inclusions

Baruah

2018

J Chem Sci

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Various non-covalently linked inorganic self-assemblies formed by the supramolecular interacting sites located at the ligands are discussed. The impetus for this rapidly growing topic on the construction of robust assemblies is elucidated by select examples that are associated with interesting structures and properties. The review includes discussion on the stabilization of different assemblies of nucleobases in the non-covalent assemblies of inorganic complexes. The participation of the guest molecules in the formation of self-assemblies with hosts to make extra space or voids for intake of the guest, water-assisted assemblies, changes in the structures guided by cations, and aggregation-induced photoluminescence in the self-assemblies of metal complexes are presented. Fine-tuning of non-covalent self-assemblies of metal complexes by changing ligands or by other components, which modify the guest recognition abilities is elucidated. The discussions are based on selected examples of self-assemblies that use supramolecular features of peripheral part of ligands or ligand of a complex that helps one to identify templates for weak interactions and for molecular recognition.

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Hierarchical organization of a robust porphyrin cage self-assembled by hydrogen bonds

Cited by 16 publications

References 32 publications

Tautomerism and Atropisomerism in Free‐Base (meso)‐Strapped Porphyrins: Static and Dynamic Aspects

Tautomerism and Atropisomerism in Free‐Base (meso)‐Strapped Porphyrins: Static and Dynamic Aspects

Influence of hydrogen bonding on excitonic coupling and hierarchal structure of a light-harvesting porphyrin aggregate

Predominantly ligand guided non-covalently linked assemblies of inorganic complexes and guest inclusions

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