Encapsulation of Acenaphthene within C‐Propan‐3‐ol‐pyrogallol[4]arene Dimeric Nanocapsules

Abstract

[a] Nanometer-scale structures have been formed in a variety of ways including covalent, non-covalent, and metal-directed assembly. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] Self-assembling, noncovalent molecular structures have been shown to form a wide range of unique host structures.[17] Previously investigated hexameric C-alkylpyrogallol [4]arene (PgC n ) nanocapsules have an interior volume of % 1250 3 , are seamed together with 72 hydrogen bonds, and are stable in nonpolar and moderately polar solvents. [18][19][20][21][22][23] These hexameric nanocapsules were shown to act as a host to multiple guest molecules, mainly pyrene derivatives. The dimeric nanocapsules that are the focus of this work are seamed together with crystallisation solvent molecules (methanol) and are capable of encapsulating a single acenaphthene molecule.Investigation into the behaviour of these entities in solution has been fairly limited, although our previous reports [24][25][26][27] have provided insight through the use of molecular spectroscopy techniques, particularly steady-state and dynamic fluorescence measurements. This ground-breaking work illustrated the potential of the PgC n nanocapsules for wide-ranging applications including molecular transport, sorting and catalysis. [20,[23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38] Previous studies of pyrene butyric acid (PBA) and pyrene butanol (PBOH) encapsulated within the hexameric C-hexylpyrogallol[4]arene (PgC 6 ) nanocapsules remarkably showed that the guest remained entrapped within the hexameric nanocapsules in solution for both systems. [24,25] Single-crystal X-ray crystallographic data revealed that the nanocapsules were mainly doubly occupied by the guest. The fluorophores inside the cavity were separated by sandwiched assembly solvent, acetonitrile. Spectroscopic and crystallographic investigations determined that both guests interacted with the interior walls of the capsule both in solid and solution states.In order to elucidate the role of guest size in encapsulation and stability of the resulting complex, the fluorescence reporter acenaphthene (AN) was investigated. AN differs from previously investigated guest molecules in both its smaller size and lack of a polar functional group within the structure. The PgC 3 OH host forms a dimeric capsule seamed with crystallisation solvent molecules to accommodate a single AN guest molecule. This varies from the hexameric capsules formed when PgC 6 building blocks were utilised to entrap pyrene derivatives. The resulting supramolecular assembly is shown in Figure 1. Alternate positions of the guest within the dimeric nanocapsule have been modelled and additonal images are included in the Supporting Information.Single-crystal X-ray diffraction studies of the pale pink crystals show that the PgC 3 OH self-assembled into a dimeric capsule containing a single AN guest molecule. Each dimeric capsule is seamed together by hydrogen-bonding mediated through four methanol solvent molecules. The interi...

Metal Organic Nanocapsules as Two-Dimensional Network Building Blocks

“… a SPE data for the dissociation reactions at the MP2/B2-PP and M05-2X/B2-PP (in parentheses) levels of theory. Data in kJ/mol. b These data were previously reported in ref b. …”

“…The authors declare no competing financial interest. XRD15: C 141.04 H 132 N 14 O 34.25 Zn 8 , M r = 3094.07, 0.13 × 0.09 × 0.02 mm, monoclinic, space group P21/n, a = 16.7257 ( 6), b = 30.6684 (10)…”

Aqueous solubilization of hydrophobic supramolecular metal–organic nanocapsules

“…[13][14][15][16][17] The encapsulation sites available within these PgC n M-based nanocapsules render them captivating candidates for practical applications such as drug delivery. 13,[18][19][20][21][22] These macrocycles, PgCs, have been shown to encapsulate several ourophore probes, such as pyrene, pyrene butanol, ADMA, pentacene and acanapthene. [18][19][20][21][22] Structurally similar to PgC n , resorcin [4]arenes (RsC n ) have also been shown to encapsulate insulin monomer as a guest moiety.…”

“…13,[18][19][20][21][22] These macrocycles, PgCs, have been shown to encapsulate several ourophore probes, such as pyrene, pyrene butanol, ADMA, pentacene and acanapthene. [18][19][20][21][22] Structurally similar to PgC n , resorcin [4]arenes (RsC n ) have also been shown to encapsulate insulin monomer as a guest moiety. 23 Although signicant efforts have been directed towards the synthesis 24 and encapsulation 18 of metal-seamed organic nanocapsules (MONCs), [25][26][27][28][29][30][31][32] their stability in solution has been less explored.…”

mPW1PW91 Calculated Structures and IR Spectra of the Conformational Stereoisomers of C-Cyanophenyl Pyrogallol[4]arene

“…[13][14][15][16][17][18][19][20][21][22][23][24] In particular, pyrogallol [4]arenes have drawn much attention since their emergence as new hydrogen-bonded dimeric and hexameric molecular receptors. [24][25][26][27][28] Many of the dimers are comprised of monomers seamed together, either directly or via hydrogen bond donor/acceptor solvent molecules. [29][30][31][32][33] The hexameric pyrogallol [4]arene spheroidal structures are held together by hydrogen bonding between the monomers.…”