Hydrophobic Encapsulation of Hydrocarbon Gases

Leontiev, Alexander V.; Saleh, and Anas W.; Rudkevich, Dmitry M.

doi:10.1021/ol070465v

Cited by 22 publications

(28 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The study of gas encapsulation by host molecules remains a challenge, with few suitable analytical techniques available 16. Recent studies of hydrocarbon gas binding by synthetic hosts in solution have relied on direct observation of the encapsulated 1 H NMR signals 16,17.…”

Section: Introductionmentioning

confidence: 99%

Substituent Effects on Xenon Binding Affinity and Solution Behavior of Water-Soluble Cryptophanes

et al. 2009

View full text Add to dashboard Cite

A water-soluble triacetic acid cryptophane-A derivative (TAAC) was synthesized and determined by isothermal titration calorimetry (ITC) and fluorescence quenching assay to have a xenon association constant of 33,000 M−1 at 293 K, which is the largest value measured for any host molecule to date. Fluorescence lifetime measurements of TAAC in the presence of varying amounts of xenon indicated static quenching by the encapsulated xenon and the presence of a second non-xenon-binding conformer in solution. Acid-base titrations and aqueous NMR spectroscopy of TAAC and a previously synthesized tri-(triazole propionic acid) cryptophane-A derivative (TTPC) showed how solvation of the carboxylate anions can affect the aqueous behavior of the large, nonpolar cryptophane. Specifically, whereas only the crown-crown (CC) conformer of TTPC was observed, a crown-saddle (CS) conformer of TAAC was also detected in aqueous solution.

show abstract

Section: Introductionmentioning

confidence: 99%

Substituent Effects on Xenon Binding Affinity and Solution Behavior of Water-Soluble Cryptophanes

et al. 2009

View full text Add to dashboard Cite

show abstract

“…[1][2][3][4][5][6][7][8][9] It allows for a puristic understanding of the solvophobic driving force for the formation of discrete host-guest complexes [10] and has additional potential for gas storage, uptake, and separation, thus complementing solid-state applications of porous materials [11,12] or surface-immobilized macrocycles. [1][2][3][4][5][6][7][8][9] It allows for a puristic understanding of the solvophobic driving force for the formation of discrete host-guest complexes [10] and has additional potential for gas storage, uptake, and separation, thus complementing solid-state applications of porous materials [11,12] or surface-immobilized macrocycles.…”

mentioning

confidence: 99%

Strong Binding of Hydrocarbons to Cucurbituril Probed by Fluorescent Dye Displacement: A Supramolecular Gas‐Sensing Ensemble

Florea¹,

Nau²

2011

Angewandte Chemie

View full text Add to dashboard Cite

The inclusion of small hydrocarbons into molecular container compounds in solution has received considerable attention. [1][2][3][4][5][6][7][8][9] It allows for a puristic understanding of the solvophobic driving force for the formation of discrete host-guest complexes [10] and has additional potential for gas storage, uptake, and separation, thus complementing solid-state applications of porous materials [11,12] or surface-immobilized macrocycles. [13] Studies on the precipitation of complexes between the smallest alkanes with a-cyclodextrin date back to the 1950s. [14] Subsequently, synthetic hosts such as cryptophanes, [1] self-assembling capsules, [2][3][4][5] and hemicarcerands [6,7] have been investigated for their potential to entrap small hydrocarbons. Herein, we describe a highly sensitive fluorescence-based method for the quantification of volatile hydrocarbons binding with cucurbituril. We observe exceptionally strong, highly selective, and reversible binding in aqueous solution.Cucurbit[n]urils (CBn) are water-soluble, highly symmetric pumpkin-shaped synthetic macrocycles, [15,16] and their unique supramolecular chemistry is presently unfolding. [17,18] They are well-established to bind organic ammonium ions through a combination of hydrophobic interactions inside the nonpolar inner cavity and ion-dipole interactions with the carbonyl portals. While a CB5 derivative has been reported to bind very small guests such as methane and acetylene, [12, 19] the homologue which holds most promise for hydrocarbon binding is CB6, [20] the original cucurbituril, which possesses an intermediary size to allow inclusion of guests with up to seven heavy atoms into its inner cavity. [18,21] Unfortunately, CB6 has an intrinsically low water solubility of about 30 mm, which complicates the determination of actual binding constants. [21,22] In particular, it prevents 1 H NMR titrations, which have been routinely employed in all previous studies on solution-phase gas binding by molecular containers. [1][2][3][4][5][6][7][8][9] The binding of xenon with CB6 has been studied by 129 Xe NMR spectroscopy in the presence of 0.2 m Na 2 SO 4 , [23] where the solubility is increased (but where also the binding strength suffers). Alternatively, an alkylated CB6 derivative with higher water solubility has been employed, which was also investigated by isothermal titration calorimetry, to afford a binding constant of 3400 m À1 with xenon. [24] The binding constants, which we report herein for several simple hydrocarbons, are much larger than those observed for xenon, and, in fact, the largest ones reported for neutral guests with CB6. [18] In several cases, they exceed those previously observed for any molecular container. [1][2][3][4][5][6][7][8][9] In the quest for a convenient method to monitor volatile hydrocarbon binding to CB6, we selected an indicator displacement strategy [25] based on our recently developed anchor dye approach. [26] In detail, compound 1 possesses a putrescine anchor for strong binding with CB6, [27] and a ...

show abstract

“…36 The driving force for the encapsulation of guest trimers leading to inclusion complexes 26 is the π-π stacking between melamine units of the host and the central ring of anthraquinone derivatives. Trimeric capsules 19 and hydrogen-bonded alizarin trimer 20 3 form the inclusion complexes in which alizarin trimer 20 3 is encapsulated between the two rosette layers. The complexation of trimers of 21 and of 22 occurs in a similar way.…”

Section: Methodsmentioning

confidence: 99%

“…Calixarene-based capsules are a topic of numerous reports; so dimeric capsules [1][2][3][4][5] as well as species of higher multiplicity [6][7][8][9] are intensively studied due to their interesting properties and application possibilities. Calixarene-based capsules of higher multiplicity are mainly trimeric and hexameric species, albeit tetrameric and octameric compounds are also known.…”

Section: Introductionmentioning

confidence: 99%