Synthesis and structure of a triptycene-based nanosized molecular cage

A triptycene-based nanosized molecular cage was designed and efficiently synthesized by Eglington-Glaser coupling reaction, and its structure was determined by NMR, MS spectrometry and X-ray analysis. Moreover, it was found that the cage molecules could pack into a microporous structure in the solid state and 1,3,5-trimethylbenzene molecules were located in the channels.     

Novel triptycene-based cylindrical macrotricyclic host: synthesis and complexation with paraquat derivatives

[reaction: see text] A novel triptycene-based cylindrical macrotricyclic polyether containing two dibenzo[24]crown-8 cavities has been synthesized and proved to be a highly efficient host for the complexation with paraquat derivatives. Consequently, a new kind of very stable pseudorotaxane-type complex was formed in solution and in the solid state.     

Synthesis of a novel triptycene-based molecular tweezer and its complexation with paraquat derivatives

[reaction: see text] A novel triptycene-based molecular tweezer has been synthesized, and its complexation with paraquat derivatives in solution and in the solid state has been studied. Due to its electron-rich cavity, the molecular tweezer could form stable complexes with paraquat derivatives with different functional groups. Moreover, it was also found that formation of the complexes was caused by a charge transfer interaction and the complexes dissociated upon two one-electron reduction of the bipyridinium ring.     

A Portrait of the OPE as a Biological Agent

Oligophenylene ethynylenes, known as OPEs, are a sequence of aromatic rings linked by triple bonds, the properties of which can be modulated by varying the length of the rigid main chain or/and the nature and position of the substituents on the aromatic units. They are luminescent molecules with high quantum yields and can be designed to enter a cell and act as antimicrobial and antiviral compounds, as biocompatible fluorescent probes directed towards target organelles in living cells, as labelling agents, as selective sensors for the detection of fibrillar and prefibrillar amyloid in the proteic field and in a fluorescence turn-on system for the detection of saccharides, as photosensitizers in photodynamic therapy (due to their capacity to highly induce toxicity after light activation), and as drug delivery systems. The antibacterial properties of OPEs have been the most studied against very popular and resistant pathogens, and in this paper the achievements of these studies are reviewed, together with almost all the other roles held by such oligomers. In the recent decade, their antifungal and antiviral effects have attracted the attention of researchers who believe OPEs to be possible biocides of the future. The review describes, for instance, the preliminary results obtained with OPEs against severe acute respiratory syndrome coronavirus 2, the virus responsible for the COVID-19 pandemic.     

固相萃取-气相色谱/质谱联用法测定儿童手推车中3种有机磷酸酯阻燃剂

有机磷酸酯是一类重要的磷系阻燃剂,由于其具有类似持久性有机污染物(persistent organic pollutants, POPs)的性质,欧美等国家已纷纷设立相关法规限制其在儿童用品中的使用。目前国际和国内均未有儿童手推车中有机磷酸酯阻燃剂的检测标准。本文建立了儿童手推车中3种有机磷酸酯阻燃剂的超声萃取-弗罗里硅土固相萃取柱净化-气相色谱/质谱检测方法。该方法的加标回收率为89.5%~107.3%,检出限(3S/N)为0.01 mg/kg,定量限(10S/N)为0.1 mg/kg,能较好地排除基质干扰,适用于儿童手推车软垫材料中3种有机磷酸酯的定性和定量分析。37个样品的分析结果表明,磷酸三(2-氯丙基)酯(TCPP)的检出率为81.1%,含量范围为1.0~15312.8 mg/kg,依据欧盟玩具新指令2014/79/EU, TCPP超标(> 5 mg/kg)率为32.4%;其中2个样品中还检出了磷酸三(2-氯乙基)酯(TCEP)和磷酸三(1,3-二氯-2-丙基)酯(TDCP),含量范围为6.2~44.1 mg/kg,均已超标。可见,市场上的儿童手推车存在较高的有机磷酸酯阻燃剂暴露风险。     

Synthesis, self-assembly, and photophysical properties of cationic oligo(p-phenyleneethynylene)s

Three series of cationic oligo p-phenyleneethynylenes (OPEs) have been synthesized to study their structure-property relationships and gain insights into the transition from molecular to macromolecular properties. The absorbance maxima and molar extinction coefficients in all three sets increase with increasing number of repeat units; however, the increase in λ(max) between the oligomers having 2 and 3 repeat units is very small, and the oligomer having 3 repeat units shows virtually the same spectra as a p-phenyleneethynylene polymer having 49 repeat units. A computational study of the oligomers using density functional theory calculations indicates that while the simplest oligomers (OPE-1) are fully conjugated, the larger oligomers are nonplanar and the limiting "segment chromophore" may be confined to a near-planar segment extending over three or four phenyl rings. Several of the OPEs self-assemble on anionic "scaffolds", with pronounced changes in absorption and fluorescence. Both experimental and computational results suggest that the planarization of discrete conjugated segments along the phenylene-ethynylene backbone is predominantly responsible for the photophysical characteristics of the assemblies formed from the larger oligomers. The striking differences in fluorescence between methanol and water are attributed to reversible nucleophilic attack of structured interfacial water on the excited singlet state.     

液液提取-固相萃取-高效液相色谱-串联质谱测定人体血液中16种有机磷酸酯

人体体液中有机磷酸酯(OPEs)浓度的测定对于了解人体OPEs的暴露水平以及评估人体健康风险具有重要意义.然而,目前的研究大多数集中于尿液中OPEs代谢物含量的分析测定,将其作为人体OPEs暴露的生物标志物,而对人体血液中OPEs的分析研究较少,仅有的少量研究涉及的OPEs种类有限.该研究在优化前处理过程(固相萃取,S...     

Determination of organophosphorous flame retardants in fish tissues by matrix solid-phase dispersion and gas chromatography

Organophosphate esters (OPEs), utilized as flame retarding agents and/or plasticizers, are almost ubiquitous in environmental compartments, and biota and foods could be contaminated by bioaccumulation or during the treatment processes. A multiresidue method is proposed for the determination of 13 OPEs in fish tissues: analytes were simultaneously extracted and purified using the matrix solid phase dispersion technique and then determined by gas chromatography with nitrogen–phosphorus detection. The main parameters affecting extraction yield and selectivity, such as the type of dispersant material, clean-up co-sorbent, rinse and elution solvents, were evaluated to obtain lipid-free extracts and quantitative recoveries for OPEs. Under optimal conditions, 0.5 g of samples was dispersed with 2 g Florisil and 1 g anhydrous sodium sulphate and transferred to a solid phase extraction cartridge containing 1 g alumina. The lipids were removed using 5 mL n-hexane/dichloromethane (1:1) and analytes were recovered with 10 mL n-hexane/acetone (6:4) and directly analysed. The method developed provided recoveries between 70 and 110% for different kinds of fish, and the day-to-day variability was between 1 and 9%. This procedure constitutes the first analytical method for the analysis of OPEs in a food matrix and it is applicable to analyse a large number of samples to evaluate the occurrence and sources of OPEs in biota and foods.     

Solid state self-assembly of triptycene-based catechol derivatives by multiple O-H…O hydrogen bonds

Single crystals of two triptycene-based catechol derivatives 1 and 2 were obtained,and their X-ray crystal structural studies showed that the two tecton molecules had different conformations in the solid state,and they could self-assemble into interesting 3D networks with solvent molecules included inside, in which multiple O-H…O hydrogen bonds played important roles.     

Improved and new syntheses of potential molecular electronics devices

New syntheses of ethyl and nitro substituted oligo(phenylene ethynylene)s (OPEs) have been developed. To further explore whether the presence of nitro functionality in OPEs leads to switching and memory capabilities, new nitro substituted OPEs have been designed and synthesized. An isatogen-based system, a structure that is isomeric to the nitro OPE, has been synthesized. Additionally, pyridine-based and chromium-based compounds have been synthesized. We surmise that redox reactions of these candidates may impart switching capabilities and electrochemical studies are shown. U-shaped OPEs were synthesized to inhibit leakage of metals deposited during formation of top contacts on self-assembled monolayers (SAMs). The OPEs contain either thiol-based moieties or isonitrile groups to enable formation of SAMs on metal substrates.     

Selective templated complexation of a cylindrical macrotricyclic host with neutral guests: three cation-controlled switchable processes

A novel triptycene-based cylindrical macrotricyclic host 1 containing an anthracene unit and two dibenzo [24]crown-8 moieties was synthesized, and its cation binding properties were studied. It was found that the host could not only form complex with the paraquat derivative 4, but also show selective templated complexation with pyromellitic diimide 2 and anthraquinone 3 in the presence of lithium and potassium ions, respectively. Consequently, two novel cascade complexes with neutral molecules as bridging species were formed in solution and in the solid state, which were structurally studied by NMR, MS spectra, and X-ray methods. Moreover, we also found that the association and dissociation of the complexes could be easily achieved by the addition and removal of lithium or potassium ions, which resulted in three cation-controlled switchable processes.     

Organophosphate esters in water,suspended particulate matter (SPM) and sediments of the Minjiang River,China

As organic pollutants of emerging concern, organophosphate esters (OPEs) have shown toxicity to organisms after entering the water environment. However, research on OPEs in freshwater in Southwest China is very limited. The levels, distribution and partitioning behavior of OPEs in the Minjiang River and their influencing factors is still unknown. In this study, six OPEs, tri-n-butyl phosphate (TnBP), tri(2-chloroethyl)-phosphate (TCEP), trichloropropyl phosphate (TCPP), triphenyl phosphate (TPhP), tributoxyethyl phosphate (TBEP), and tris(2-ethylhexyl)-phosphate (TEHP), were determined in surface water, suspended particle matter (SPM) and sediments of the Minjiang River. The results showed that the average concentrations of Σ₆OPEs in surface water, SPM and sediments of the Minjiang River were 199.32 ± 124.95 ng/L, 38463.79 ± 45641.89 ng/g dry weight (dw) and 76.45 ± 28.00 ng/g dw, respectively. High concentrations of OPEs were detected in SPM samples, indicating that more attention should be paid to pollution in SPM. It is worth noting that the variation trend of OPEs in SPM was almost opposite to that in water but basically similar to that in sediment. The proportions of alkyl OPEs in Σ₆OPEs increased from surface water to SPM and sediments. Alkyl OPEs were the main pollutants in SPM (10.44%–80.88% of Σ₆OPEs, mean of 54.52%) and sediments (59.08%–81.30% of Σ₆OPEs, mean of 68.91%), whereas chlorinated OPEs were the most abundant components in surface water (43.16%–75.99% of Σ₆OPEs, mean of 55.50%). The water-sediment partition coefficient (logK_OC) of OPEs was 4.97–7.58, while the water-SPM partition coefficient was 6.71–10.00. No significant correlations were found between logK_OW and logK_OC. K_OW was not the main factor affecting the distribution of OPEs in the Minjiang River, China.     

Roof-shaped halide-bridged bimetallic complexes via ring expansion reaction

Binucleating behavior of rigid triptycene-based ligands has been studied. It has been demonstrated that trans-spanned transition-metal mononuclear complexes bearing 1,8-bis(diisopropylphosphino)triptycene (L1) and 1-diisopropylphosphino-8-diphenylphosphinotriptycene (L2) react with an appropriate transition-metal precursor via a ring-expansion pathway to form unusual bimetallic quasi-closed structures. New palladium and rhodium complexes featuring strongly bent (ca. 115 degrees ) M2(mu-Cl2) cores with very closely spanned metal centers (less than 3 A) have been prepared using the described ring-expansion reaction and have been fully characterized. Despite a constrained arrangement of the binuclear system, halogen bridges in all new compounds were stable in both the solid state and solution showing no tendency for dissociation even in the presence of added Lewis bases. Spontaneous resolution of the dissymmetric Pd2(mu-Cl)2Cl2(1-diisopropylphosphino-8-diphenylphosphinotriptycene) (2) into enantiopure antipodes is discussed as well.     

C_(18)膜萃取/液相色谱-质谱联用法测定极地水体中有机磷酸酯

建立了C_(18)膜萃取/液相色谱-质谱联用技术测定极地水体中10种有机磷酸酯(OPEs)的方法。根据优化后的样品前处理及仪器方法,利用C_(18)膜富集4 L水体中的10种OPEs,经二氯甲烷超声提取,在电喷雾正离子模式下,采用选择反应监测(SRM)模式进行分析,线性相关系数为0.994 4~0.999 9。10种OPEs的加标回收率为64.1%~115%,方法检出限为0.08~0.55 ng/L。该方法适用于极地水体中10种OPEs的分析,利用该方法对北极水体样品中的10种OPEs进行检测,测得冰川融水中∑OPEs的质量浓度为0.64~6.64 ng/L,海水中∑OPEs的质量浓度为0.09~2.03 ng/L。     

Development of an ultra-high-performance liquid chromatography-tandem mass spectrometry method for high throughput determination of organophosphorus flame retardants in environmental water

Widely used as flame retardants, organophosphate esters (OPEs) are now broadly present in the indoor and outdoor environments. Currently available liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods share some drawbacks with gas chromatography (GC) methods, including time consuming, limited target OPEs, incomplete separation capability for some OPEs and low throughput. In this study, a fast and high throughput LC-MS/MS method was developed. For the first time, all the twelve OPEs that have been studied in literature, ranging from the very polar and volatile trimethyl phosphate to the very hydrophobic and non-volatile tris(2-ethylhexyl) phosphate, were separated within 11 min. Different from previous studies, we found that the blank contamination was mainly from organic mobile phase rather than the enrichment process, and it can be efficiently eliminated by using acetonitrile rather than methanol as the organic phase of the mobile phase. The signal to noise ratio (S/N) was significantly improved by using 0.1% formic acid as an organic modifier. The method exhibited high throughput and sensitivity and can baseline separate 11 of the 12 OPEs studied within 11 min with LOQs ranging from 2 to 6 ng/L. The relative standard deviations were in the range of 2-10%. For both reagent water and river water, the spiked recoveries of OPEs ranged from 70 to 110%, except for the very polar and volatile trimethyl phosphate that has recovery below 10%. The developed procedure was successfully applied to study the OPE contamination of the Songhua River, and it was found that all the target OPEs were detected with total concentrations of around 1 μg/L in the river waters.     

5,12‐Diacetyl‐5,12‐dihydroquinoxalino[2,3‐b]quinoxalines: Solid‐State Fluorescence,AIE Properties,and Orbital Switching by Substituent Effect

The compound 5,12‐diacetyl‐5,12‐dihydroquinoxalino[2,3‐b]quinoxaline 1 a and its derivatives were prepared, and their solid‐ and solution‐state spectroscopic properties were studied; 1 a shows stronger fluorescence in solution than in the solid state due to aggregation caused by self‐quenching. Phenyl‐ or alkoxy‐substituted derivatives 1 b – d show solid‐state fluorescence with moderate quantum yields of about Φ=0.12–0.15, although the corresponding values are 0.01–0.07 in solution. The spectroscopic properties of alkoxy‐substituted derivatives were hardly changed compared to 1 a and 1 b , although 1 a and 1 b have similar absorption and fluorescence maxima in solution and in the solid state. DFT calculations indicate that orbital switching occurs between HOMO and HOMO‐1 and HOMO‐2 due to orbital interactions with introduced substituents. Crystal structure analysis revealed that the molecules have bent structures around tertiary nitrogen atoms and form a characteristic dimeric structure.     

Steady-state and time-resolved studies of 2,7-carbazole-based conjugated polymers in solution and as thin films: determination of their solid state fluorescence quantum efficiencies

The UV–Vis absorption spectra and the luminescence properties of poly(N-octyl-2,7-carbazole) (POC) and poly(N-octyl-2,7-carbazole-alt-9,9-dioctyl-2,7-fluorene) PCF have been investigated in solution and in the solid state (thin films). No aggregate and/or excimer formation has been detected in these polymeric systems. From time-resolved fluorescence measurements in solution and in the solid state, the fluorescence efficiencies of the thin films have been estimated. It is found that the fluorescence efficiencies of these polycarbazoles in the solid state are quenched, as compared to those measured in fluid solutions, but remain relatively high (φ_F0.40), making them promising materials for electroluminescent devices.     

Metal‐Free Facile Synthesis of Multisubstituted 1‐Aminoisoquinoline Derivatives with Dual‐State Emissions

Although isoquinoline is a good traditional fluorescent structural unit, most of its derivatives emit fluorescence in solution and a few of them can emit solid‐state fluorescence as well. Herein, a series of multisubstituted 1‐aminoisoquinoline derivatives were synthesized by a simple reaction of a readily available 4H‐pyran derivative and secondary amines. The reaction had advantages of metal‐free, mild conditions, simple operation, and good yields, which was realized by a ring‐opening and sequential ring‐closing mechanism. These 1‐aminoisoquinoline derivatives were found to exhibit interesting dual‐state emissions. In the solution, they emitted strong blue fluorescence at about 458 nm. In the solid state, they emitted solid‐state blue fluorescence at 444–468 nm with high fluorescence quantum yields of 40.3–98.1%. Crystal structural analyses indicated that solid‐state emissions of these compounds originated from twisted molecular conformations and the resultant loose stacking arrangements. Furthermore, their solid‐state fluorescence wavelengths were demonstrated to depend on molecular conformations rather than stacking arrangements. The discovery of these 1‐aminoisoquinolines with multiple reaction sites provides new possibilities for the development of solid‐state fluorescent materials based on the traditional isoquinoline skeleton.     

Triptycene-based expanded oxacalixarenes: synthesis, structure, and tubular assemblies in the solid state

Owing to the unique 3D rigid structure of triptycene, two novel expanded oxacalixarenes 5a and 5b as a pair of diastereomers were efficiently synthesized in a single step by the SNAr reaction of 2,7-dihydroxytriptycene with 2,3,5,6-tetrachloropyridine in the presence of cesium carbonate. Similarly, two pairs of other triptycene-based expanded oxaxalixaenes 7a,7b and 9a,9b could also be obtained by the SNAr reactions of 2,7-dihydroxytriptycene with 1,5-difluoro-2,4-dinitrobenzene and cyanuric chloride, respectively. The structures of the expanded oxacalixarenes were studied by NMR, MS spectra, and X-ray crystal structure analyses. It was found that the expanded oxacalixarene 9b showed a dynamic interconversion between boat and chair conformations. Moreover, we also found that the expanded oxacalixarenes 5a, 5b, and 9a could all assemble into organic tubular structures and further porous architectures in the solid state, in which chlorine bonding, such as C-Cl...Cl, C-Cl...O, and C-Cl...pi interactions, played an important role.     

Fluorescence Emission of Self-assembling Amyloid-like Peptides: Solution versus Solid State

Analysis of the intrinsic UV-visible fluorescence exhibited by self-assembling amyloid-like peptides in solution and in solid the state highlights that their physical state has a profound impact on the optical properties. In the solid state, a linear dependence of the fluorescence emission peaks as a function of excitation wavelength is detected. On the contrary, an excitation-independent emission is observed in solution. The present findings constitute a valuable benchmark for current and future explanations of the fluorescence emission by amyloids.