Supramolecular Host-Guest Hydrogel Based on γ-Cyclodextrin and Carboxybenzyl Viologen Showing Reversible Photochromism and Photomodulable Fluorescence

Much effort has been devoted to the development of supramolecular hydrogels due to their broad applications and conveniently controllable properties. Here, we demonstrate a novel supramolecular host-guest hydrogel, which is constructed by the host γ-CD complexed with the guest 1-(4-carboxybenzyl)-4,4'-bipyridinium chloride (1⁺·Cl^-) through the π···π interaction, hydrogen bonding, and host-guest interactions. The supramolecular hydrogel [1⁺@γ-CD]_n exhibits reversible electron transfer photochromic behavior and photomodulable fluorescence. The excellent photochromic and fluorescence properties support the practical utility of the supramolecular hydrogel as a visual display and anti-counterfeiting material.

A light-responsive molecular switch based on cucurbit[7]uril and 1,1'-bis(benzyl)-4-[2-(4-pyridyl)-vinyl]-pyridinium dibromide displaying white light emission

By using ¹H NMR, ESI-MS and UV spectra, a novel light-responsive molecular switch constructed using 1,1'-bis(benzyl)-4-[2-(4-pyridyl)-vinyl]-pyridinium (1²⁺) and cucurbit[7]uril (Q[7]) is demonstrated. The E- to Z-isomerization of the double bond in 1²⁺ results in the transition of the switching states from the 1 : 2 complex E-1²⁺@Q[7]₂ to the stable 1 : 1 complex Z-1²⁺@Q[7]. In particular, both the 1 : 2 complex and the 1 : 1 complex can emit cold white fluorescence under UV light.

Encapsulation of l-valine, d-leucine and d-methionine by cucurbit[8]uril

The binding interactions of cucurbit[8]uril (Q[8]) with l-valine, d-leucine, and d-methionine, both in aqueous solution and solid state, have been studied by 1H NMR spectroscopy and X-ray crystallography.

An inclusion complex of cucurbit[7]uril with benzimidazolyl benzyl viologen exhibits fluorescence and photochromic properties

A self-assembled supramolecular inclusion complex of Q[7] with benzimidazolyl benzyl viologen exhibits interesting fluorescence emission and reversible photochromism.

Detecting Pesticide Dodine by Displacement of Fluorescent Acridine from Cucurbit[10]uril Macrocycle

According to a simple guest-replacement fluorescence turn-on mechanism, we constructed a fluorescent probe system based on cucurbit[10]uril (Q[10]) and protonated acridine (AD) to detect the pesticide dodine (DD). Formation of a homoternary inclusion complex AD₂@Q[10] in both aqueous solution and solid state was studied by means of ¹H NMR spectroscopy and X-ray crystallography. Although AD can emit strong fluorescence in aqueous solution, the homoternary inclusion complex AD₂@Q[10] does not exhibit any fluorescence. Upon the addition of the pesticide DD into the aqueous solution of AD₂@Q[10], the AD molecules in the Q[10] cavity are displaced by the pesticide DD, and strong fluorescence recovers. The fluorescent probe system based on Q[10] and AD provided a wide determination of DD from 0 to 4.0 × 10^-5 mol·L^-1 with a low limit of detection of 1.827 × 10^-6 mol·L^-1. The guest-replacement fluorescence turn-on mechanism is also confirmed by ¹H NMR spectroscopy. Further, the fluorescent probe can directly detect DD residues in real agricultural products, and obvious fluorescence signal was observed under UV irradiation.

Electron transfer photochromism of solid-state supramolecules constructed by cucurbit[n]uril (n = 5–8) and 1-(4-carboxybenzyl)-4-[2-(4-pyridyl)-vinyl]-pyridinium chloride

Solid-state supramolecular complexes of a bispyridinium ethylene derivative with cucurbit[n = 5–8]uril exhibit fast responsive photochromic properties, which are caused by the electron transfer from the host to the guest.

Separation of phenylenediamine isomers by using decamethylcucurbit[5]uril

This work investigated the binding interactions between decamethylcucurbit[5]uril (Me₁₀Q[5]) and phenylenediamine isomers, and developed a strategy to isolate phenylenediamine isomers.

Symmetrical-Tetramethyl-Cucurbit[6]uril-Driven Movement of Cucurbit[7]uril Gives Rise to Heterowheel [4]Pseudorotaxanes

Two novel heterowheel [4]pseudorotaxanes consisting of cucurbit[7]uril (Q[7]) and symmetrical-tetramethyl-cucurbit[6]uril (TMeQ[6]) were constructed via the multirecognition mechanism, in which Q[7] can rotate freely around the horizontal axis, while TMeQ[6] cannot. In the construction process, due to strong repulsive forces between carbonyl portals of two neighboring wheels, the dethreading and movement of the wheels along the axle was observed. The dissociation of the [4]pseudorotaxanes was also discussed.

Selective recognition and determination of phenylalanine by a fluorescent probe based on cucurbit[8]uril and palmatine

This paper demonstrated a simple and validated fluorescence enhancing method to selectively recognize and discriminate the amino acid phenylalanine (Phe). ¹H NMR spectroscopy reveal that the palmatine (PAL) can be encapsulated into the cucurbit [8]uril (Q [8]) in aqueous solution to form stable 1:2 host-guest inclusion complex PAL₂@Q [8], which exhibits moderate intensity fluorescence property. Interestingly, the addition of the Phe into the inclusion complex PAL₂@Q [8] leads to dramatically enhancing of the fluorescence intensity. In contrast, the addition of any other natural amino acids into the inclusion complex PAL₂@Q [8] gives no fluorescence variation. Furthermore, it is easy to detect the concentration of Phe in target aqueous solution according to the linear relationship between fluorescence intensity and concentration of the Phe.

Supramolecular chemistry of substituted cucurbit[n]urils

This review covers important advances in the field of substituted cucurbit[n]urils.

The lanthanide contraction effect and organic additives impact the coordination structures of lanthanide ions with symmetrical octamethyl-substituted cucurbit[6]uril ligands

Two facts, the lanthanide contraction effect and the “bridge” role of organic additives, impact the coordination structures of lanthanide ions with OMeQ[6] ligands.

Encapsulation and removal of aniline by di-cyclohexanocucurbit[6]uril

The binding behaviors of Cy2Q[6] and Cy6Q[6] with aniline, p-methylaniline, and p-phenyldiamine were investigated by various techniques, which suggests that Cy2Q[6] is a promising candidate for aniline removal because of its oval cavity.

Correction: Multiple noncovalent interaction constructed polymeric supramolecular crystals: recognition of butyl viologen by para-dicyclohexanocucurbit[6]uril and α,α′,δ,δ′-tetramethylcucurbit[6]uril

Correction for ‘Multiple noncovalent interaction constructed polymeric supramolecular crystals: recognition of butyl viologen by para-dicyclohexanocucurbit[6]uril and α,α′,δ,δ′-tetramethylcucurbit[6]uril’ by Zhi-You Xiao et al., Org. Chem. Front., 2017, DOI: 10.1039/c7qo00708f.

Construction of a Molecular Switch and Selector under Electrochemical Control

In this work, we designed and synthesized a special axle guest hexyldimethyl(ferrocenylmethyl)ammonium (1 ⁺ ) bromide. The binding interactions of 1 ⁺ and its oxidized form 1 ²⁺ with cucurbit[7]uril (Q[7]) and cyclohexanocucurbit[6]uril (Cy6Q[6]) were investigated by ¹H NMR, cyclic voltammogram, and isothermal titration calorimetry techniques. Our data indicate that both hosts Cy6Q[6] and Q[7] can form stable [2]pseudorotaxanes with 1 ⁺ in their different redox states. Most importantly, the combination and dissociation of the hosts with the guest as well as the binding location can be controlled by electrochemical means, which develops a special molecular switch and selector.

Host-guest complexation of cucurbit[8]uril with two enantiomers

Host-guest complexation of cucurbit[8]uril (Q[8]) with two enantiomers, D-3-(2-naphthyl)-alanine (D-NA) and L-3-(2-naphthyl)-alanine (L-NA), has been fully investigated. Experimental data indicate that double guests reside within the cavity of Q[8] in both aqueous solution and solid state, generating highly stable homoternary complexes D-NA2@Q[8] and L-NA2@Q[8].

Endo/exo binding of alkyl and aryl diammonium ions by cyclopentanocucurbit[6]uril

Binding interactions of cyclopentanocucurbit[6]uril (CyP₆Q[6]) with a series of alkyl and aryl diammonium ions were investigated. CyP₆Q[6] exhibits endo and exo binding modes with the guests, which depends on the size and shape complementarity between the host and the guests.

Multiple noncovalent interaction constructed polymeric supramolecular crystals: recognition of butyl viologen by para-dicyclohexanocucurbit[6]uril and α,α′,δ,δ′-tetramethylcucurbit[6]uril

Binding interactions of butyl viologen (BV⁺) with two kinds of cucurbit[6]uril derivatives were investigated, showing the formation of polymeric supramolecular crystals through multiple noncovalent interactions.

Host-guest complexation of di-cyclohexanocucurbit[6]uril and hexa-cyclohexanocucurbit[6]uril with alkyldiammonium ions: a comparative study

The host-guest complexation of symmetrical di-cyclohexanocucurbit[6]uril (Cy2Q[6]) and hexa-cyclohexanocucurbit[6]uril (Cy6Q[6]) with a series of alkyldiammonium ions (H(3+)N(CH(2))nNH(3+), n = 2-8) has been studied both in solution and in the gas phase. (1)H NMR data indicate that all alkyldiammonium ions have inclusion interactions with both hosts except for the ethanediammonium ion. In addition, if the alkyl chain of the alkyldiammonium ion is longer than n = 5 methylene groups, compressed conformation may occur, which depends on the cavity shape of the hosts and the length of the alkyl chain. Isothermal titration calorimetry (ITC) studies point out that the host-guest complexations of both hosts with the latter five alkyldiammonium ions are enthalpically driven. The comparison of the thermodynamic data reveals that the enthalpies of the van der Waals interactions contribute more to the host-guest complexation enthalpy than the ion-dipole interactions. The enthalpic gain arises from the van der Waals interactions and the reduction of entropy upon the host-guest complexation is strongly affected by the cavity shape of the host. Gas phase structures of long alkyldiammonium guests within both hosts are completely different from those in aqueous solution.

Host–guest complexation of HMeQ[7] with alkyldiammonium ions and alkyldiamines: a comparative study

The host–guest complexations of HMeQ[7] with a series of alkyldiammonium ions and alkyldiamines have been investigated, indicating that the driving forces strongly depend on the features of the guests.

Mixed behavior of p-phenylenediaminium guest binding with the inverted cucurbit[6]uril host

The binding interaction between inverted cucurbit[6]uril (iQ[6]) and p-phenylenediaminium both in the solid state and in aqueous solution has been investigated by X-ray crystallography, (1)H NMR spectroscopy and isothermal titration calorimetry (ITC). The experimental results suggest that the binding interaction between iQ[6] and p-phenylenediaminium may generate two different types of complexes in the solid state: one is an inclusion structure and the other is a sandwich structure. In aqueous solution, the iQ[6] host has an ability to accommodate the p-phenylenediaminium guest and in-out guest exchange is fast on the NMR time scale. ITC data indicate that the complexation of iQ[6] with p-phenylenediaminium is entropy driven.

Selection and crossbreeding in relation to plumage color inheritance in three chinese egg type duck breeds (anas platyrhynchos)

In China and South East Asia, the duck (common duck) is important in egg production for human consumption. Plumage color is a breed characteristic and of economic importance, together with egg production. Our aim in this study was to investigate the inheritance of plumage color in three Chinese indigenous egg-type duck breeds, Shan Ma (S), Putian White (F) and Putian black (P), and some of their crossbreds. These three breeds have different plumage color and are used in crossbreeding. The crossbred laying ducks F×(P×S) and F×(S×P) showed highly improved laying ability but heterogeneous plumage color. Genotypes at four relevant loci were investigated by studying down color and pattern in ducklings after crossbreeding. F₁ ducklings from the matings F×S and S×F, P×S, and S×P were classified into four classes of plumage color (the Shan Ma plumage color, black, white, or multicolored) over three generations. Parents were selected for the Shan Ma plumage color of their progeny. In the fourth generation, P male and P female ducks were selected according to the frequency of the desired class of plumage color (Shan Ma) of their F1 progeny to obtain the so-called “Brown Putian Ma duck”. The Shan Ma duck genotype was identified as having the restricted mallard color pattern (M^RM^R), full expression of any of the patterns or colors (CC), no extended black (ee) and no brown dilution D (D). The Putian White genotype was recessive white (cc), no extended black (ee) and no brown dilution D (D). The Putian Black genotype exhibited full expression of extended black (E gene) and no brown dilution (CCEE D [D]). It was shown that F×S and S×F tests should be implemented to eliminate the recessive white c allele in the S line and the dominant extended black E allele in the F line. It was also shown that the Brown Putian Ma obtained from Putian Black, with no extended black genotype (ee), could be used to get rid of the black plumage (E gene) in the crossbred ducks. This could provide a solution for producing 3-way crossbred ducks Putian White×(Putian-Ma ×Shan Ma) and Putian White×(Shan Ma×Putian-Ma), with the desired Shan Ma feather color.

Infantile haemangiomas: a challenge in paediatric dermatology

Infantile haemangiomas, common benign vascular tumours of childhood, are characterized by rapid growth during the first year of life and a slow regression that is usually completed at 7-10 years of age. These tumours are composed of endothelial cells with high mitotic rates and stromal components such as fibroblasts, mast cells and pericytes. Haemangiomas become a challenge when they are part of a syndrome, are located in certain areas of the body or when complications develop. The above-mentioned factors also influence the treatment modality used. However, although there remain many uncertainties regarding management, the beta-adrenergic receptor blocker propranolol is a promising new candidate for first-line systemic therapy. It produces such a dramatic and rapid response that the appearance of an infantile haemangioma should impart expeditious consideration of the risks and benefits of its use.

Heroin body packing: three fatal cases of intestinal perforation

Death from heroin body packing has been well described in the forensic literature. Most fatalities are due to drug leakage and consequent acute heroin toxicity. Recently, drug traffickers have become more sophisticated in their packaging, and the risk of rupture of drug packets is more remote. Though intestinal obstruction is a recognized risk of body packing, rarely has this resulted in death. We describe four cases of heroin body packing presenting to the Regional Medical Examiner Office in New Jersey. Death in three of these cases was due to intestinal obstruction, with resultant intestinal rupture and peritonitis. Toxicologic evaluation in these three cases was negative for opiates or other drugs of abuse. In one case, death was due to acute heroin toxicity, validated by toxicologic analysis. We briefly discuss the differing drug packaging found in these four cases and the ramifications of packaging as it relates to intestinal obstruction.

Distribution of codeine, morphine, and 6-acetylmorphine in vitreous humor

Two hundred and twenty-three vitreous humor specimens, which were obtained from a medical examiner's office, were found to be opiate positive (cutoff, 50 ng/mL) by fluorescence polarization immunoassay. All samples were analyzed for their free codeine, morphine, and 6-acetylmorphine contents by a gas chromatography-mass spectrometry protocol. 6-Acetylmorphine was found (cutoff, 10 ng/mL) in 41 specimens in the concentration range of 10-125 ng/mL. Twenty specimens had a free codeine-free morphine concentration ratio > or = 1. Eighty-five samples that were found to contain 50 ng/mL free morphine were further analyzed for their total codeine and total morphine contents. Total codeine-total morphine concentration ratios in 8 (of the 85 samples) were > or = 1, whereas this ratio in the others (only those with a codeine concentration high than 15 ng/mL were included) was significantly lower than 1. The codeine-morphine concentration ratio in vitreous humor appears to resemble that reported for blood and urine and can be used as the basis for differentiating between codeine- and morphine- (heroin-) induced fatalities.

Clinical manifestations of bronchogenic carcinoma

A retrospective clinical study was carried out on 227 pathologically proven cases of bronchogenic carcinoma from eastern Taiwan, between October 1986 and March 1990. The ratio of males to females was low (2.15:1). The most common cell type was adenocarcinoma (39.2%), with squamous cell carcinoma (36.1%) being the second most common. Adenocarcinoma contributed to 51.4% of the bronchogenic carcinoma in women and 33.5% in men. History of cigarette smoking was strongly associated with squamous cell carcinoma and small cell carcinoma. The most common symptom was a cough (69%). The majority of small cell carcinoma and squamous cell carcinoma appeared to be of the central type in location while most adenocarcinoma appeared to be of the peripheral type. Bronchoscopic examination was the most valuable method for confirming the diagnosis of bronchogenic carcinoma. Most patients presented late and only 19 cases (8.4%) underwent surgery. Aborigines have a lower risk of developing bronchogenic carcinoma. The clinical manifestations of bronchogenic carcinoma in eastern Taiwan are similar to those found in Taiwan as a whole.

Is ethanol the unknown toxin in smoke inhalation injury?

Of the 12,000 fire-related deaths occurring annually in the United States, it is estimated that 60 to 80 per cent are due to smoke inhalation. Plastic and synthetic materials which have been introduced in home construction and furnishings produce a more toxic smoke when burned. Efforts to identify a "supertoxin" in this smoke have been unsuccessful to date. An alternative approach is to examine why victims are unable to escape, and become exposed to smoke for lethal periods of time. The authors examined the circumstances of death in 39 fire victims (27 adults, 12 children) over a 25-month period. Detailed examination of the fire scene, autopsy studies, and toxicologic analysis were carried out. Position of the victim, and escape efforts were noted. Carbon monoxide was elevated in all victims, with "lethal" levels (= greater than 50%) in 21/39 victims. Cyanide was detected in 24/29 victims, but none had lethal (3 mg/L) levels present. Ethanol was detected in 21/26 adults (80%) and 0/12 children (0%). 18/26 adult victims had ethanol levels above the statutory level of intoxication (10 mg%). Victims found in bed (no escape attempt) had a mean blood ethanol level of 268 mg%, compared with a mean level of 88 mg% in those victims found near an exit (P = .006). Ethanol intoxication significantly impairs the ability to escape from fire and smoke and is a contributory factor in smoke-related mortality.