Highly selective Cu2+ detection with a naphthalimide-functionalised pillar[5]arene fluorescent chemosensor.

Ligand 1, a rim-differentiated pillar[5]arene macrocycle modified with five naphthalimide groups through click chemistry, serves as an effective ratiometric fluorescent chemosensor for Cu2+. In contrast to the monomeric naphthalimide control compound 2, which shows only monomer emission, ligand 1 demonstrates dual emission characteristics encompassing both the monomer and excimer of the naphthalimide moieties. The binding properties of ligand 1 toward 15 different metal ions were systematically investigated in CH2Cl2/CH3CN (v/v, 1 : 1) by UV-vis and fluorescence spectroscopy. Remarkably, ligand 1 exhibits exceptional selectivity for Cu2+ ions. Upon complexation with Cu2+, the excimer emission of ligand 1 diminishes, concomitant with an enhancement of its monomer emission. The binding ratio for 1·Cu2+ was determined to be 1 : 1, with an association constant of (3.39 ± 0.40) × 105 M-1 calculated using a nonlinear least-squares curve-fitting method. Furthermore, the limit of detection (LOD) was found to be 185 ± 7 nM. Our results from 1H NMR titration, high-resolution mass spectrometry analysis and density functional theory calculations of 1·Cu2+ suggest synergistic coordination between Cu2+ and the triazole groups on ligand 1.

Calix[4]arene-based Supramolecular Gels for Mercury Ion Removal in Water.

A calix[4]arene-based gelator 1, with lower-rim mono triazolylpyridine group, capable of spontaneous self-assembly into microspheres in different ethanol/H2 O mixtures, is synthesized. The concentration-dependent 1 H NMR spectra and X-ray single-crystal structure of 1 provided evidence for self-assembly of gelator 1 via cooperative interactions of intermolecular noncovalent forces. Furthermore, metallogels by self-assembly of 1 was found to exhibit remarkable selectivity toward Hg2+ ions. 1 H NMR spectra support that Hg2+ ion was bound to the nitrogen atoms of two coordination sites of 1, which composed of triazole and pyridine. Moreover, the results of field emission scanning electron microscopy and rheology experiments indicated that Hg2+ ions not only enhanced the gelling ability of gelator 1 in ethanol but also led to morphological change of its self-assembly through metal-ligand interactions. Finally, the in situ gelation, triggered by mixing a gelator solution of 1 in ethanol with water samples such as deionized (DI), tap, and lake water, leads to the effective removal of Hg(II) from a water sample which reduced from 400 to 1.6 ppm.

A highly selective chromogenic and fluorogenic chemodosimeter for dual detection of Cu2+ based on a redox-active calix[4]arene with isoxazolylchloroanthracene.

Calix[4]arene 1, with two lower-rim isoxazolylchloroanthracene groups, is shown to be not only a chromogenic but also a fluorogenic chemodosimeter for the selective sensing of Cu2+. The binding properties of ligand 1 and control compounds 2 and 3 toward metal ions in CH3CN/CHCl3 (v/v, 1 : 1) were investigated by UV-vis and fluorescence spectroscopy. The results showed that only ligand 1 was highly selective for Cu2+ ions. When complexed with Cu2+, ligand 1 displayed a new absorption band around 435 nm and the color of the solution changed from colorless to yellow. Furthermore, the fluorescence of ligand 1 was severely quenched by Cu2+ and the limit of detection (LOD) was determined to be 1.674 µM. Therefore, compound 1 is not only a chromogenic but also a fluorogenic sensor for the detection of Cu2+ ions over other metal ions examined. When complexed with ligand 1, Cu2+ was reduced to Cu+ by the free phenolic-OH of ligand 1 and concurrently the phenol was oxidized by Cu2+ to quinones. The 1H NMR, EPR, and FTIR spectra provided evidence for the redox behavior of ligand 1 with Cu2+. The isolation of calix[4]diquinone 8 and Cu(CH3CN)4ClO4 from the reaction of ligand 1 with Cu(ClO4)2 confirmed their redox reaction.

One-Pot Three-Component Synthesis of 2-Imino-1,3-Thiazolines on Soluble Ionic Liquid Support.

An efficient one-pot, three-component synthesis of 2-imino-1,3-thiazolidines and 2-imino-1,3-thiazolines using ionic liquid-tethered 2-aminobenzimidazoles was reported. The protocol includes reaction of ionic liquid attached 2-aminobenzimidazoles with isothiocyanates to afford isothioureas, followed by its base induced inter and intramolecular nucleophilic displacement reactions with 1,2-dichloroethane (EDC) which results in thiazolidine ring formation. In the next to the last step, the ionic liquid support was removed by methanolysis to deliver 2-imino-1,3-thiazolidines, which were sequentially oxidized with manganese(III) triacetate to yield 2-imino-1,3-thiazolines. The salient feature of this method is the use of 1,2-dichloroethane as a synthetic equivalent for α-haloketone to avoid the use of toxic halogenating reagents.

The Prevalence and Genotype of Human Papillomavirus from Patients with Genital Warts in Eastern Guangdong Province.

BACKGROUND: Low-risk human papillomavirus (LR-HPV) infection is the main cause of genital warts. LR- HPV genotypes 6 and 11 are associated with genital warts, but there have only been a few published studies about the genotype-specific prevalence of HPV in genital warts in China. The objective of our study was to assess the prevalence of HPV genotypes for clinical cases involving both men and women and to evaluate the potential benefit of a quadrivalent (genotypes 6, 11, 16, and 18) HPV vaccine in eastern Guangdong province of China. MATERIALS AND METHODS: A total of 696 eligible patients with genital warts were enrolled during the period Aug 2009 through Oct 2014. Specimens were collected from genital warts, the HPV GenoArray test was used for HPV detection and genotyping, which could detect 21 HPV genotypes, including genotypes 6, 11, 16, and 18. RESULTS: Among the 696 cases, 675 samples were successfully genotyped. The median age of patients was 32.1 years (range, 16-67 years). The most prevalent genotypes were HPV-6 (285/675, 42.2%), HPV-11 (265/675, 39.3%), HPV-52 (52/675, 7.7%), HPV-16 (51/675, 7.56%), HPV-81 (50/675, 7.40%) and HPV-58 (37/675, 5.48%). Low-risk genotypes predominated, with a prevalence of 96.59%. The cumulative prevalence of genotypes 6 and 11 was 78.7% (531/675), the cumulative prevalence of genotypes 16 and 18 was 11.6% (78/675), and the cumulative prevalence of genotypes 6, 11, 16, and 18 was 82.5% (557/675). CONCLUSIONS: Our results provide strong evidence that, in eastern Guangdong, different from Western countries, the most prevalent low risk HPV genotypes in patients with genital warts are 6, 11 and 81. The quadrivalent HPV vaccine could prevent 82.5% of genital warts in eastern Guangdong.

Prevalence and genotype distribution of human papillomavirus infections in women attending hospitals in Chaozhou of Guangdong province.

BACKGROUND: Human papillomavirus (HPV) infection is the main cause of cervical cancer. Limited epidemiologic data of HPV prevalence are available for women attending hospitals in southern China. This study aimed to evaluate the profiles of HPV infection and cytology status in gynecological outpatients in Chaozhou City. METHODS: A total of 2833 eligible women were enrolled. The HPV GenoArray test was used for HPV detection and genotyping. Nearly one half of the HPV positive women received liquid-based cytology test. Logistic regression analysis was performed to assess the predictable effects of age and genotype for categories of abnormal cytology. RESULTS: The prevalence of overall, high-risk, and low-risk HPV infection were 24.5%, 19.5% and 8.4%, respectively. A U-shaped age-specific prevalence curve was observed in overall HPV and high- risk HPV, but not in low-risk HPV, which declined with age increasing. The 6 most common high-risk HPV type in descending order, were types 52, 16, 58, 18, 68, and 33. Age and HPV genotype were both important determinants of abnormal cytology incidence, the older women (>45 years) and those infected with HPV type 16 and/or 18 having the highest risk for abnormal cytology. CONCLUSION: Our findings support the hypothesis that second-generation HPV prophylactic vaccines including HPV-52 and -58 may offer higher protection for women residing in Chaozhou and neighboring cities in Guangdong.

Novel ionic liquid supported-multicomponent reaction toward chimeric bis-heterocycles.

A novel multicomponent reaction between IL-anchored 2-aminobenzoimidazoles, aldehydes, and electron-deficient dienophiles has been explored. The strategy was utilized to develop a rapid parallel synthesis for novel bis-heterocyclic skeleton of benzimidazole-linked dihydropyrimidine on an ionic liquid support. This multicomponent reaction is compatible with a wide range of substrates and furnishes the new chimeric scaffolds with high purity and excellent yields. Use of the ionic liquid as a soluble support facilitates purification by simple precipitation along with advantages like high loading capacity, homogeneous reaction conditions, and monitoring of the reaction progress by conventional NMR spectroscopy.

Design and synthesis of new biprivileged molecular scaffolds: indolo-fused benzodiazepinyl/quinoxalinyl benzimidazoles.

The present article describes the design and synthesis of new biprivileged molecular scaffolds with diverse structural features. Commercially available, simple heterocyclic building blocks such as 4-fluoro-3-nitrobenzoic acid, 2-chloro-3-nitrobenzoic acid, and indoline were utilized for the synthesis of the novel heterocycles. Pictet-Spengler-type condensation was used as a key step to construct tetracyclic indolo-benzodiazepines and indolo-quinoxalines linked with substituted benzimidazoles. Analysis of single crystals of representative compounds showed that these molecular skeletons have the potential to present various substituents with distinct three-dimensional orientations.

Epidemiologic characterization of human papillomavirus infection in rural Chaozhou, eastern Guangdong Province of China.

BACKGROUND: Human papilloma virus (HPV) infection was the main cause of cervical cancer. There were only a few reports and detailed data about epidemiological research of HPV infection in rural population of China. MATERIALS AND METHODS: The cervical cells of rural Chaozhou women were collected, and multiplex real time PCR was firstly performed to detect high-risk HPV (HR-HPV) infection, which could detect 13 types of HR-HPV (types 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, and 68). Then, HPV-positive samples were typed by HPV GenoArray test. RESULTS: HR-HPV DNA was detected by multiplex real time-PCR in 3830 of 48559 cases (7.89%). There was a peak incidence in age of 55-60 years group, and a lower incidence in who lived in plain group compared with suburban, mountain and seashore group. 3380 cases of HPV positive sample were genotyped, 11.01% (372/3380) cases could not be classified, among the typed 3008 cases, 101 cases were identified without HR-HPV type infection, 2907 cases were infected with one HR-HPV type at least, the 6 most common HR-HPV types in descending order of infection, were type 52 (33.4%, 16 (20.95%), 58 (15.93%), 33 (9.94%), 68 (9.22%) and 18 (8.36%). The combined prevalence of HPV types 16 and 18 accounted for 28.52% of total infection. However, type 52 plus 58 presented 48.23% of total infection. 2209/2907 cases were infected with a single HPV type and 698/2907 cases were infected with multiple types, and multiple infection constituent ratio increased with age, with a peak incidence in age 55-60 years group. CONCLUSIONS: Our findings showed low prevalence of HPV vaccine types (16 and 18) and relatively high prevalence of HPV-52 and -58, support the hypothesis that the second-generation HPV vaccines including HPV-52 and -58 may offer higher protection for women in rural Guangdong Province.

Synthesis and photophysical properties of self-assembled metallogels of platinum(II) acetylide complexes with elaborate long-chain pyridine-2,6-dicarboxamides.

A series of platinum(II) acetylide complexes with elaborate long-chain pyridine-2,6-dicarboxamides was synthesized. These metal complexes are capable of immobilizing organic solvents to form luminescent metallogels through a combination of intermolecular hydrogen bonding, aromatic π-π, and van der Waals interactions. Fibrillar morphologies were identified by TEM for these metallogels. Unique photophysical properties associated with the sol-to-gel transition have been disclosed with luminescence enhancement at elevated temperatures, which is in sharp contrast to typical thermotropic organogels or metallogels reported in the literature. Such unusual luminescence enhancement is attributed to the increased degree of freedom at higher temperatures that results in the formation of favorable molecular aggregates in the excited state through enhanced aromatic π-π and metallophilic Pt(II)···Pt(II) interactions. Structurally similar Pt-bp3 is not able to gel any common organic solvents. The inability of Pt-bp3 to form gels illustrates the importance of gelation to the macroscopic photophysical properties; Pt-bp3 does not show emission enhancement at elevated temperatures due to its low tendency to form strong aggregates in the ground state.

Diagnosing appendicitis at different time points in children with right lower quadrant pain: comparison between Pediatric Appendicitis Score and the Alvarado score.

BACKGROUND: Acute appendicitis is the most common abdominal emergency in clinical surgery. This study was designed to compare the diagnostic value of the Pediatric Appendicitis Score (PAS) with that of the Alvarado score based on different time points in children with right lower quadrant (RLQ) abdominal pain. METHODS: This prospective cohort study comprised 1,395 children (aged 3-18 years) with RLQ abdominal pain between 2005 and 2009. The patients were scored by the pediatric emergency physicians. Receiver operating characteristic (ROC) curves were used to determine the appropriate cutoff scores of the Alvarado and PAS systems. The sensitivity and specificity, and area under ROC curve were calculated for both systems. RESULTS: The AUCs of the Alvarado system were all higher than those of the PAS system (day 1: 0.09 vs. 0.87; day 2: 0.87 vs. 0.84; day 3: 0.88 vs. 0.82). The best appropriate cutoff scores were seven (days 1 and 2) and six (day 3) on the PAS and six (days 1 and 2) and seven (day 3) on the Alvarado system. CONCLUSIONS: The preliminary data show that the best cutoff score of Alvarado and PAS systems vary with the different time points of RLQ pain presentation. It may provide helpful information for primary or emergency physicians to determine whether the patient should undergo surgical consultation.

Significant change between primary and repeated serum laboratory tests at different time points in pediatric appendicitis.

OBJECTIVE: The aim of the work is to determine whether the change between primary and repeated serum inflammatory markers measured 8-12 h later may improve diagnostic accuracy in pediatric appendicitis. METHODS: The study group comprised 258 pediatric patients with clinically suspected appendicitis admitted to the pediatric emergency department from 2005 to 2007. The significant changes in serum parameters between primary and repeated examinations were selected as the discriminating variables. The receiver operating characteristic curves were used to determine the cut-off values of the changes between two examinations in predicting appendicitis. RESULTS: Receiver operating characteristic analysis showed that the cut-off values for the change in total neutrophils (3.0%) on the first day after the onset of symptoms (day 1), the changes in C-reactive protein concentration (4.5 mg/l) and in bands (1%) on day 2, and the change in C-reactive protein concentration (15.0 mg/l) on day 3 were significant serum parameters in predicting pediatric appendicitis. CONCLUSION: Repeated serum laboratory tests at different time points during the progression of acute appendicitis may be helpful in predicting pediatric appendicitis in the pediatric emergency department.

Synthesis of electron deficient acene derivatives via a bidirectional iterative elongation reaction.

Previously, we developed an iterative elongation methodology to synthesize acene esters, nitriles, and imides. The strategy uses the concept of bidirectional synthesis, and we can now make a series of electron deficient anthracene, tetracene, and pentacene derivatives via the bidirectional iterative elongation protocol. Central units, used to initiate the bidirectional elongation, were synthesized by employing a double anionic Fries rearrangement as the key step. The photophysical and electrochemical properties of these novel electron acceptors are investigated and interpreted based on the electron withdrawing power of the substitutions. An excited state charge transfer was proposed for one compound to account for its peculiar fluorescent behavior.

A selective colorimetric Hg2+ probe featuring a styryl dithiaazacrown containing platinum (II) terpyridine complex through modulation of the relative strength of ICT and MLCT transitions.

A series of platinum(II) terpyridine complexes featuring an aminostilbene donor-acceptor framework was synthesized. The complex with a dithiaazacrown moiety exhibits a highly sensitive and selective colorimetric response to a Hg(2+) cation through modulation of the relative strength of ICT and MLCT transitions. The results from (1)H NMR titration suggest the existence of a weak Pt(II)···Hg(II) metallophilic interaction at low Hg(2+) concentration.

New chromogenic and fluorescent probes for anion detection: formation of a [2 + 2] supramolecular complex on addition of fluoride with positive homotropic cooperativity.

Two new chromogenic and fluorescent probes for anions have been designed, synthesized, and characterized. These probes contain multiple hydrogen bonding donors including hydrazine, hydrazone, and hydroxyl functional groups for potential anion interacting sites. Despite the possible flexible structural framework due to the presence of sp3 carbon linkage, X-ray structure analysis of probe 2 displayed an essentially planar conformation in the solid state owing to strong crystal packing interactions comprising a combination of favorable pi-pi stacking effect and hydrogen bonding to cocrystallized CH3OH molecules. Both probes 1 and 2 display orange color in DMSO solution and show fairly weak fluorescence at room temperature. Binding studies revealed that both probes 1 and 2 show noticeable colorimetric and fluorescent responses only to F-, OAc-, and H2PO4- among the nine anions tested (F-, Cl-, Br-, I-, OAc-, H2PO4-, HSO4-, ClO4-, and NO3-). The general trend of the sensitivity to anions follows the order of F- > OAc- > H2PO4- > Cl- > Br- approximately I- approximately HSO4- approximately ClO4- approximately NO3-. A 1:2 (probe to anion) binding stoichiometry was found for probe 1 with OAc- and H2PO4- and probe 2 with F-, OAc-, and H2PO4-. The binding isotherm of probe 1 to F- was found to be complicated with apparent multiple equilibria occurring in solution. The formation of an aggregated supramolecular complex upon addition of fluoride is proposed to rationalize the observed optical responses and is supported by ESI mass spectrometry and pulsed-field gradient NMR spectroscopy. Data analysis suggests that the binding of probe 1 to F- shows positive homotropic cooperativity.

Synthesis, photophysical, and anion-sensing properties of quinoxalinebis(sulfonamide) functionalized receptors and their metal complexes.

We report the synthesis, characterization, and photophysical properties of a series of organic receptors and their corresponding ReI and RuII metal complexes as anion probes featuring bis(sulfonamide) interacting sites incorporating highly chromophoric pi-conjugated quinoxaline moieties. The interactions with various anions were extensively investigated. These probe molecules are capable of recognizing F-, OAc-, CN-, and H2PO4- with different sensitivities. The probe-anion interactions can be easily visualized via naked-eye colorimetric or luminescent responses. Probe 1 has the weakest acidic sulfonamide N-H protons and therefore simply forms hydrogen-bonding complexes with F-, OAc-, CN-, and H2PO4-. Probe 2 undergoes a stepwise process with the addition of F- and OAc-: formation of a hydrogen-bound complex followed by sulfonamide N-H deprotonation. Direct sulfonamide N-H deprotonation occurs upon the addition of CN-, while only a hydrogen-bound complex forms with the H2PO4- ion for probe 2 in a dimethyl sulfoxide (DMSO) solution. Similar probe-anion interactions occur in probe 3 with the addition of F-, CN-, or H2PO4-. However, only a genuine hydrogen-bound complex forms in the presence of the OAc- ion in a DMSO solution of probe 3 because of the subtle difference in the pKa values of sulfonamide N-H protons when probes 2 and 3 are compared. Coordination of probe 1 to a ReI center or probe 2 to a RuII center increases the intrinsic acidity of sulfonamide N-H protons and results in an enhanced sensitivity to anions.

Dipyrrole carboxamide derived selective ratiometric probes for cyanide ion.

Two anion probes 1 and 2 featuring the dipyrrole carboxamide moiety for anion recognition have been prepared. These structurally simple anion probes display great selectivity for the cyanide anion over other common inorganic anions in semiaqueous environment via the formation of cyanohydrin derivatives. [structure: see text]