Clear Color Change Research Articles

IDENTIFIKASI DAN ANALISIS KADAR FLAVONOID EKSTRAK GETAH ANGSANA (Pterocarpus indicus Willd) DI DUSUN WANATH KECAMATAN LEIHITU KABUPATEN MALUKU TENGAH

Background: Medicinal plants have many benefits that make it a traditional medicine for society. One of the medicinal plants used by the community, especially the Wanath Hamlet community, is the angsana gum (Pterocarpus indicus Willd.) In treating diseases.
 Method: This study aims to identify and analyze flavonoid levels in angsana sap (Pterocarpus indicus Willd.) In Wanath Hamlet qualitatively (flavonoid color test) and quantitative (flavonoid content analysis).
 Results: The results show a change in color to yellow which indicates that the sap is positive for flavonoids, while in aquades it shows clear color changes which indicate negative.
 Conclusion: Qualitative test (color test) of angsana gum extract positively contains flavonoids when identified with several flavonoid reagents which produce yellow

Natural Plant Extracts as Acid-Base Indicator and Determination of Their pKa Value

Commonly used indicators for acid-base titrations are synthetic, and this work was focused to identify the eco-friendly natural indicators and to determine their pKa values. The analytical potential of the flower extracts is very promising as seen in its application in acid-base titrimetry. These selected flower extracts were found to perform well in titrating strong acid-strong base than in weak acid-strong base. We have obtained a sharp and clear colour change from red to brownish yellow for the Bougainvillea glabra extract, from red to yellow for the Bauhinia purpurea extract, and from red to brownish yellow for the Impatiens balsamina extract. All the three flower extracts gave clear colour change with acids and bases, and the colour change was maintained with different acids and bases. The sharp contrast between their colours in acid and base made the pigment suitable for use as acid-base indicators. As these flower extracts have very simple,cost-effective, environment friendly extraction procedure and excellent performance with sharp colour change in end points of the titrations, it would be possible to replace the standard indicators being used in conventional laboratories with natural flower indicators.

Smart bandage dyed with sensor probe encapsulated in alginate for wound healing monitoring ضمادة ذکية مصبوغة بصبغة استشعار مغلفة بألجينات الکالسيوم لرصد التئام الجروح

الملخص العربي تم تطوير ضمادة ذکية لمتابعة التئام الجروح ، وذلک اعتمادا علي تغير اللون عند التئام الجروح. يمکن أن يؤدي تطوير اداة استشعار لدرجة الحموضة بالتقنية اللونية النسيجية إلى استخدام تطبيقات فعالة ، حيث أنه يمثل إمکانية متابعة الاس الهيدروجيني بطريقة سريعة باستخدام خامة رخيصة ومرنة. تم تحضير صبغة التراي سيانوهيدرازون واستخدامها کمادة استشعار لدرجة الحموضة والقاعدية. حيث تم تغليف صبغة التراي سيانوهيدرازون المتجاوبة لدرجة الاس الهيدروجيني کمادة داخلية والجينات الکالسيوم کجدار خارجي للکبسولة ، والتي تم تحميلها على شاش قطني بطريقة الغمر. هذه التغيرات في اللون القابل لاعادة الاستخدام والتي تتجاوب مع تغيرات الأس الهيدروجيني کانت نتيجة لتخليق الشحنة الاليکترونية العالية لمرکب التراي سيانوهيدرازون أنيون المنتج الذي يؤدي إلى انتاج جزيء من نوع الکوينويد حيث تم استخدام هذا الملون في المواد النسيجية التقنية لاکسابها القدرة على استشعار الرقم الهيدروجيني. اعتمد النهج المعتمد في هذه الدراسة على صباغة القطن الشاش باستخدام صبغة التراي سيانوهيدرازون محملة داخل کابسولات الکالسيوم الجينات لمتابعة التئام الجروح. أظهر الشاش المصبوغة تغيرا واضحا في اللون عند التعرض لمحاليل قاعدية وحمضية کما هو موضح بإحداثيات اللون. تشير نتائجنا إلى تغير واضح في اللون يظهر بالعين المجردة ، من اللون البرتقالي إلى اللون الأرجواني ، والتي يمکن التعرف عليها على سطح الأقمشة المستخدمة. تم دراسة التشکل السطحي وتکوين الشاش القطني المعالج تحت المجهر الإلکتروني الماسح الضوئي ، الأشعة السينية المشتتة للطاقة ، ورسم الخرائط العنصري. تمت دراسة الشاش القطني المعالج من خلال استکشاف نفاذية الهواء ، والصلابة ، وثبات اللون Abstract Novel in-situ dressing bandage-based disposable probe that changes color upon wound healing was developed. Developing colorimetric technical textile pH-sensor can lead to attractive end-use applications as it represents the potential for inexpensive, fast, flexible pH-sensors. Herein we describe the preparation of tricyanofuran-hydrazone based disperse colorant to act as a color changeable pH-sensor. The pH responsive tricyanofuran-hydrazone was encapsulated as a core material in Ca-alginate microcapsule as a wall-former, which was loaded onto a cotton gauze by padding. This reversible color change depending on pH variations was due to charge delocalization of tricyanofuran-hydrazone anion form generated that led to a quinoid-type molecular switching. This tricyanofuran-hydrazone colorant was employed for use in technical textile materials with a pH sensing capability. The approach adopted in the present study was based on dyeing of cotton gauze using tricyanofuran-hydrazone that can afford numerical results for the pH of the wound fluid. The dyed gauze matrix showed a clear reversible color change upon exposure to acid-base solutions as indicated by color coordinates. Our results indicate an obvious color change shown to the naked eye, from orange to purple, which can be recognized at the surface of the employed fabrics when exposed to basic conditions. The surface morphology of the treated cotton gauze was investigated under scanning electron microscopy, energy-dispersive X-ray, and mapping.The treated cotton gauze was studied by exploring of the air-permeability, stiffness, and colorfastness.

Chromo-Fluorogenic Detection of Soman and Its Simulant by Thiourea-Based Rhodamine Probe.

Here, we introduced a novel thiourea-based rhodamine compound as a chromo-fluorogenic indicator of nerve agent Soman and its simulant diethyl chlorophosphate (DCP). The synthesized probe N-(rhodamine B)-lactam-2-(4-cyanophenyl) thiourea (RB-CT), which has a rhodamine core linked by a cyanophenyl thiosemicarbazide group, enabled a rapidly and highly sensitive response to DCP with clear fluorescence and color changes. The detection limit was as low as 2 × 10−6 M. The sensing mechanism showed that opening of the spirolactam ring following the phosphorylation of thiosemicarbazides group formed a seven-membered heterocycle adduct, according to MS analysis and TD-DFT calculations. RB-CT exhibited high detecting selectivity for DCP, among other organophosphorus compounds. Moreover, two test kits were employed and successfully used to detect real nerve agent Soman in liquid and gas phase.

A novel bis(dihydroxypropyl) viologen-based all-in-one electrochromic device with high cycling stability and coloration efficiency

Electrochromism and related devices have been studied for a few decades from both fundamental and technological point of view. At the present stage, screening electrochromic materials with excellent properties is still an interesting job. In our previous work, we have demonstrated that hydroxyalkyl viologens could exhibit satisfying electrochromic behavior. Further, in this paper, the bis(dihydroxyalkyl) viologen, (1,1‘-bis(2,3-dihydroxypropyl) 4,4‘-bipyridine derivative dichloride, DHPV2+2Cl-, was synthesized and incorporated as an electrochromic chromophore in the all-in-one electrochromic devices (ECDs) on the basis of poly (vinyl butyal) (PVB)-carbonate and poły (vinyl alcohol) (PVA)-borax gel electrolytes, respectively. It was found that DHPV2+ 2Cl- in PVB-based gel ECDs underwent reversible switching between transparent and deep blue hue, whereas the clear color changes from colorlessness to amaranth in PVA-borax-based ones upon the potential ranges from 0 V to −1.0 V. For PVB-based gel ECD, spectroelectrochemical studies demonstrated that it only needs a low coloration voltage down to −0.6 V, and exhibites high coloration efficiency (η) up to 301 cm2/C. The optical contrast of it only reduces by 1% after consecutive operation for 10000 cycles between −1.0 V and 0 V, demonstrating an excellent cycling stability of this kind of device. The ECD based on PVA-borax gel modified with glycerol shows burgundy, and good electrochromic performance. It is interesting to note that a relatively large-area PVB-based gel electrochromic devices up to 168 cm2 was realized, the driving voltage and response time being −1.5 V and 12 s, respectively, for blue-violet coloration state. The advantages of electrochromic properties exhibited by 1,1‘-bis(2,3-dihydroxypropyl) viologen dichloride over those reported can be regarded as a pronounced improvement for organic electrochromic materials, and are expected to set the stage for novel electrochromic devices such as smart window and display applications and so forth.

Fluorescent Cadmium Bipillared-Layer Open Frameworks: Synthesis, Structures, Sensing of Nitro Compounds, and Capture of Volatile Iodine.

Fluorescent Cd metal-organic frameworks (MOFs), [Cd2 (dicarboxylate)2 (NI-bpy-44)2 ] (dicarboxylate=benzene-1,4-dicarboxylate (1,4-bdc, 1), 2-bromobenzene-1,4-dicarboxylate (Br-1,4-bdc, 2), 2-nitrobenzene-1,4-dicarboxylate (NO2 -1,4-bdc, 3), biphenyl-4,4'-dicarboxylate (bpdc, 4); NI-bpy-44=N-(pyridin-4-yl)-4-(pyridin-4-yl)-1,8-naphthalimide)), featuring non- and twofold interpenetrating pcu-type bipillared-layer open structures with sufficient free voids of 58.4, 51.4, 51.5, and 41.4 %, respectively, have been hydro(solvo)thermally synthesized. MOFs 1-4 emitted solid-state blue or cyan fluorescence emissions at 447±7 nm, which mainly arose from NI-bpy-44 and are dependent on the incorporated solvents. After immersing the crystalline samples in different solvents, that is, H2 O and DMSO (1 and 2) as well as nitrobenzene and phenol (1-4), they exhibited a remarkable fluorescence quenching effect, whereas o-xylene and p-xylene (4) caused significant fluorescence enhancement. The sensing ability of MOFs 1-4 toward nitro compounds carried out in the vapor phase showed that nitrobenzene and 2-nitrophenol displayed detectable fluorescence quenching with 1, 2, and 4 whereas 4-nitrotoluene was an effective fluorescence quencher for 1 and 2; this is most likely attributed to their electron-deficient properties and higher vapor pressures. Moreover, MOFs 1-4 are highly reusable for quick capture of volatile iodine, as supported by clear crystal color change and also by immense fluorescence quenching responses owing to the donor-acceptor interaction. Low-pressure CO2 adsorption isotherms indicate that activated materials 1'-4' are inefficient at taking up CO2 .

A self-rechargeable electrochromic battery based on electrodeposited polypyrrole film

Polypyrrole (PPy) film doped with p-toluenesulfonate has been grown on indium doped tin oxide (ITO) coated glass by electrochemical polymerization. The PPy film, aluminum (Al) sheet and KCl solution are assembled into a bi-functional electrochemical device exhibiting self-powered electrochromic device and self-rechargeable battery characteristics. As an electrochromic device, the maximum optical modulation of the PPy/Al device is 59.0% at the wavelength of 698.5 nm. The original black device will become yellow after connecting its two electrodes with a response time of 6.5 s. As a battery, the capacity of the PPy/Al device is 75.25 mAh g−1 when it was initially discharged at a constant current density of 1.0 A g−1. The open circuit voltage of the PPy/Al device is 0.94 V. The charging-discharging processes of the PPy/Al device accompany a clear color change. So the capacity of the PPy/Al device can be known from the color of the device. The PPy/Al device can recover its color and capacity after disconnecting its two electrodes, which is attributed to the spontaneous transformation of PPy film from its neutral state (yellow) to p-type doped state (black) by the oxidation of oxygen.

Design, synthesis, crystal structure and cytotoxicity studies of colorimetric fluorescent “OFF-ON” probes for rapid detection of hydrogen sulfide based on Cu(II) complex

Four colorimetric fluorescent probes based on copper(II) complexes were synthesized and the molecular structures were characterized by X-ray diffraction, ESI-HRMS and elemental analysis. When exposed to HS−, the synthesized probes showed significant color changes from yellow to red and remarkable increase of fluorescence intensity (over 80-fold). What's more, the interaction of host-guest could be completed in 2 min. However, no clear color and fluorescence intensity changes were observed in the presence of other anions (AcO−, H2PO4−, F−, Cl−, Br−, I−, SO42−, SO32−, CO32−, Cys and GSH). The synthesized colorimetric fluorescent probes could detect HS− rapidly and conveniently. Cytotoxicity studies indicated that the synthesized fluorescent probes were low cytotoxicity in Hela cells and may be used to detect H2S level in vivo.

PH and Temperature Dual-Responsive Plasmonic Switches of Gold Nanoparticle Monolayer Film for Multiple Anticounterfeiting.

Two-dimensional (2D) gold nanoparticle (Au NP) monolayer film possesses a lot of fascinating peculiarities, and has shown promising applications in photoelectrical devices, catalysis, spectroscopy, sensors, and anticounterfeiting. Because of the localized surface plasmon resonance (LSPR) property predetermined by the natural structure of metal nanoparticles, it is usually difficult to realize the reversible LSPR transition of 2D film. In this work, we report on the fabrication of a large-area free-standing Au NP monolayer film with dual-responsive switchable plasmonic property using a pH- or thermal-responsive dendronized copolymer as a stimuli-sensitive linker. In this system, an oligoethylene-glycol-based (OEG-based) dendronized copolymer (named PG1A) with pH or temperature sensitivity was first modified onto the surface of a Au NP. Then, polyethylene glycol dibenzyl aldehyde (PEG-DA) was introduced to interact with the amino moieties from PG1A before the process of oil-water interfacial self-assembly of NPs, resulting in an elastic, robust, pH- or temperature-sensitive interpenetrating network among Au NPs in monolayer films. In addition, the film could exhibit reversibly plasmonic shifts of about 77 nm and inherent color changes through varying temperature or pH. The obtained free-standing monolayer film also shows an excellent transferable property, which can be easily transferred onto substrates such as plastic molds, PDMS, copper grids, and silicon wafers. In virtue of these peculiarities of the free-standing property, special plasmonic signal, and homologous macroscopic color, the transferred film was primely applied to an anticounterfeiting security label with clear color change at the designed spots, providing a new avenue to plasmonic nanodevices with various applications.

A simple colorimetric chemosensor with highly performance for detection of cyanide and copper ions and its practical application in real samples

Two novel and simple azo-based compounds with electron-withdrawing and electron-donating groups (M1 and M2) were synthesized by the diazotization procedure. The synthesized compounds were then applied for detection of important ions in aqueous solutions of acetonitrile. Sensor M1 with electron-withdrawing group (EWG) showed distinct colorimetric responses towards CNˉ (light yellow to red) and Cu2+ (light yellow to dark yellow). Through titration experiment, the detection limit (LOD) of M1 for CNˉ and Cu2+ ions sensing were found to be nano molar (nM) level. Job’s plot based on spectroscopic data showed the complexes formation between M1 and ions has the stoichiometric ratio of 1:1 (M1-CNˉ and M1-Cu2+). In addition, the binding constants for M1 towards CNˉ and Cu2+ were determined using the Benesi-Hildebrand equation. Furthermore, the M1-based test papers strips were successfully used to the rapid detection of CNˉ ions in semi‐aqueous medium. Importantly, sensor M1 was applied to detect CNˉ and Cu2+ in real water samples and apple seeds samples. However, for M2, containing electron-donating group (EDG), no clear color changes were observed in the presence of investigated ions.

Fabrication and Investigation of Crystalline Non-Porous Conductive Coordination Network Compounds

During the last years, surface-bound coordination network compounds (CNCs) have found application for sensing purposes (electrical, optical, and magnetic read-out), charge storage, electrochromic and optoelectronic layers, transparent coatings, bipolar switches, thermoelectric materials, catalytic, photocatalytic and light harvesting applications [1]. However, most of these applications require electrically conductive coordination network compounds (CCNCs). This requirement severely limits the choice of CNCs for the above-mentioned applications. Hexacyanometallates are coordinative networks with high electrical and ion conductivity that possess interesting redox properties and tuneable electrochemical redox transitions associated with clear colour changes [2]. We developed and characterized CCNCs such as copper hexacyanoferrate as thin crystalline films and characterized their optical, magnetic, electrical and dielectric properties. Thin films of these compounds were fabricated on gold and silicon oxide coated by self-assembled, cyanide-terminated monolayers using alternating immersion in their precursor solutions. Atomic force microscopy (AFM) confirms the formation of copper hexacyanoferrate with cubic structure on the gold surface (Fig. 1). Fig. 1: AFM image of copper hexacyanoferrate film on a cyanide-terminated self-assembled monolayer on gold surface via layer-by-layer method. X-ray diffraction (XRD) analysis confirmed the crystalline nature of the films. The thin films can be switched by exploiting the redox chemistry of the metal centres. The modulation of the electrical transport properties provides great potential benefits for numerous future applications in microelectronic device technologies. Structural and electronic changes of the films were probed by X-ray photoelectron spectroscopy (XPS) and polarization modulation infrared reflection absorption spectroscopy (PM IRRAS) before and after electrochemical oxidation and reduction [3]. Results demonstrate the possibility for electrochemical switching of the material properties for each compound but also indicates the complications in those transitions originating in the existence of different structures and defects in which (mobile) alkali metal cations may or may not reside in the pores and provide charge compensation. Acknowledgement(s) Financial supports from DFG priority programme (SPP1928, Wi1617/24) is gratefully acknowledged.

Carboxylesterase-2-Selective Two-Photon Ratiometric Probe Reveals Decreased Carboxylesterase-2 Activity in Breast Cancer Cells.

Human carboxylesterase-2 (CE2) is a carboxylesterase that catalyzes the hydrolysis of endogenous and exogenous substrates. Abnormal CE2 levels are associated with various cancers, and CE2 is a key mediator of anticancer prodrugs, including irinotecan. Here, we developed a two-photon ratiometric probe for detecting CE2 activity using succinate ester as a recognition site for CE2. The probe showed high selectivity to CE2, a clear emission color change, high photostability, and bright two-photon microscopy (TPM) imaging capability, allowing the quantitative detection of CE2 activity in live cells. Using TPM ratio analysis, we show for the first time that CE2 activity was much lower in breast cancer cells than in normal cells. In CE2 overexpression studies, cancer cells had a markedly enhanced sensitivity to the cytotoxic effect of irinotecan, corresponding well with the TPM ratio of the probe. These results may provide useful information for quantitatively measuring CE2 activity in situ and predicting the responsiveness to anticancer drugs.

Cu(Ⅱ) triggering redox-regulated anti-aggregation of gold nanoparticles for ultrasensitive visual sensing of iodide

In this study, we proposed a novel anti-aggregation of gold nanoparticles (AuNPs) strategy for colorimetric sensing of iodide ions (I−) regulated by the redox reaction between the target ions and the ion cross-linking agent. Cu2+ as interlinking ion can induce aggregation of arginine capped AuNPs (Arg-AuNPs) due to the formation of Arg-Cu2+-Arg analogous structure resulting from the chelation between Cu2+ and arginine, with a clear color change of solution from red to blue. In the presence of I−, however, Cu2+ would be readily reduced owing to the formation of CuI, AuNPs underwent a transformation from an aggregation to a dispersion state depending on the concentration of I−, leading color changes from blue to red. The corresponding color variation in the process of anti-aggregation of AuNPs can be monitored through UV–vis spectrophotometer or by the naked-eye, making quantitative analysis of I− feasible in a convenient colorimetric or visual way. The assay only took 5 min, showing high sensitivity with a lowest detectable concentration of 10 nM and excellent selectivity for I− over other anions tested, which was successfully applied for the detection of I− in drinking water and table salt samples.

Highly selective and sensitive coumarin-triazole-based fluorometric 'turn-off' sensor for detection of Pb2+ ions.

Exposure to even very low concentrations of Pb2+ is known to cause cardiovascular, neurological, developmental, and reproductive disorders, and affects children in particular more severely. Consequently, much effort has been dedicated to the development of colorimetric and fluorescent sensors that can selectively detect Pb2+ ions. Here, we describe the development of a triazole-based fluorescent sensor L5 for Pb2+ ion detection. The fluorescence intensity of chemosensor L5 was selectively quenched by Pb2+ ions and a clear color change from colorless to yellow could be observed by the naked eye. Chemosensor L5 exhibited high sensitivity and selectivity towards Pb2+ ions in phosphate-buffered solution [20mM, 1:9 DMSO/H2 O (v/v), pH8.0] with a 1:1 binding stoichiometry, a detection limit of 1.9nM and a 6.76 × 106 M-1 binding constant. Additionally, low-cost and easy-to-prepare test strips impregnated with chemosensor L5 were also produced for efficient of Pb2+ detection and proved the practical use of this test.

New analytical methodology for analysing S(IV) species at low pH solutions by one stage titration method (bichromatometry) with a clear colour change. Could potentially replace the state-of-art-method iodometry at low pH analysis due higher accuracy.

A new, faster and more reliable analytical methodology for S(IV) species analysis at low pH solutions by bichromatometry is proposed. For decades the state of the art methodology has been iodometry that is still well justified method for neutral solutions, thus at low pH media possess various side reactions increasing inaccuracy. In contrast, the new methodology has no side reactions at low pH media, requires only one titration step and provides a clear color change if S(IV) species are present in the solution. The method is validated using model solutions with known concentrations and applied to analyses of gaseous SO2 from purged solution in low pH media samples. The results indicate that bichromatometry can accurately analyze SO2 from liquid samples having pH even below 0 relevant to metallurgical industrial processes.

Development of Natural Anthocyanin Dye-Doped Silica Nanoparticles for pH and Borate-Sensing Applications

Anthocyanin belongs to a large group of phenolic compounds called flavonoids. It is found primarily in fruits, flowers, roots and other parts of higher plants. Within the black carrot, it has been found that the cyanidin component 1,2 diol was the major anthocyanine. Since the terminal thiols potentially display chemical interactions with borate additives, anthocyanin from the black carrot can act as a sensing material for detecting borate in the environment. As a natural dye, anthocyanin responds to pH change of the medium. Here, we present an application of black carrot dyes for pH sensing and for the detection of borate additives within meats. The dyes were encapsulated within a mesoporous silica (SiO2) matrix in order to prevent the sensing materials from dissolution into the aqueous medium. The encapsulation was done in situ during preparation of silica nanoparticles (size from 100 nm to 500 nm) following an advanced Stober method. These anthocyanin-encapsulated silica nanoparticles show a clear color change from green in an aqueous solution free of borate to GRAY-red in the presence of borate additive and red (pH 2) to green (pH 10).

Synthesis and Electrochromic Properties of Star-Shaped Oligomers with Phenyl Cores.

A series of star-shaped conjugated oligomers, 1,3,5-tri(2'-thienyl) benzene (3TB), 1,3,5-tri(3',4'-ethylenedioxythienyl) benzene (3EB), 1,3,5-tri[5',2"-(3",4"-ethylenedioxy-thienyl)-2'-thienyl] benzene (3ETB), and 1,3,5-tri[5',2"-(3",4"-ethylenedioxy-thienyl)-2'-thienyl]-4-(3',4'-ethylenedioxythienyl)benzene (3TB-4EDOT), were synthesized. The star-shaped polymer, poly(1,3,5-tri[5',2"-(3",4"-ethylenedioxythineyl)-2'-thienyl]benzene) (P3ETB), was also prepared. The electrochemical and electrochromic properties of these conjugated oligomers and polymer were investigated. These oligomer and polymer films showed reversible, clear color changes upon electrochemical doping and dedoping. The color of the P3ETB film reversibly changed from orange to blue under doping and dedoping. The switching times for doping and dedoping were 1.2 and 0.9 s, respectively.

Carbon Textiles Modified with Copper-Based Reactive Adsorbents as Efficient Media for Detoxification of Chemical Warfare Agents.

Carbon textile swatch was oxidized and impregnated with copper hydroxynitrate. A subsample was then further heated at 280 °C to form copper oxide. The swatches preserved their integrity through the treatments. As final products, they exhibited remarkable detoxification properties for the nerve agent surrogate dimethyl chlorophosphate (DMCP). Based on the amount of reactive copper phases deposited on the fibers, their adsorption capacities were higher than those of the bulk powders. After 1 day exposure to DMCP (1:1 weight ratio adsorbent/DMCP), 99% of the initial amount of DMCP was eliminated. A synergistic effect of the composite components was clearly seen. GC-MS results showed that the main surface reaction product was chloromethane. Its formation indicated hydrolysis as a detoxification path. Surface analyses showed phosphate bonding to the fibers and formation of copper chloride. The appearance of the latter species results in a clear textile color change, which suggests the application of these fabrics not only as catalytic protection agents but also as sensors of nerve agents.

Design and Luminescence Chromism of Fused Boron Complexes Having Constant Emission Efficiencies in Solution and in the Amorphous and Crystalline States

Mechanochromic luminescent molecules often suffer from critical loss of luminescence intensity during phase transitions in the solid state. In this study, we present mechanochromic luminescent molecules that can provide clear color changes with constant emission intensity during phase transitions. It was reported that the class of aggregation‐induced emission (AIE)‐active boron complexes can present intense emission by freezing intramolecular motions. According to this mechanism, we designed a complex with a fused ligand to preserve the enhanced emission in the aggregated state in the AIE during phase transitions between the solution, amorphous, and crystalline states. From optical measurements, it was shown that the synthesized boron complexes present bright emission in various phases. In particular, as we expected, the luminescence color was clearly altered during phase transition, whereas the emission intensity changed only slightly. Finally, we also found that diverse luminescence colors were obtained from each polymorph and for various substituents as induced by the substituent effect. The results in the series of mechanistic studies show that electronic interactions and π–π interactions can modulate the electronic conjugation system of the complexes without causing loss of emission efficiency.

Colorimetric Detection of Cu2+ and Fluorescent Detection of PO43– and S2– by a Multifunctional Chemosensor

A simple multifunctional chemosensor 1 was synthesized by a combination of N-aminophthalimide and 8-hydroxyjulolidine-9-carboxaldehyde. The sensor 1 showed a clear color change toward Cu2+ from pale to deep yellow and significant fluorescence enhancements toward PO43– and S2–. The detection limit (0.14 μM) for Cu2+ ion was below the World Health Organization (WHO) guideline for drinking water (31.5 μM). The sensor 1 could be used to quantify copper ion in real water samples. In addition, the sensor 1 could detect phosphate and sulfide with the fluorescent enhancements in aqueous solution. The sensing mechanism of Cu2+ by 1 was proposed to be an intramolecular charge transfer (ICT) and those of PO43– and S2– by 1 were proposed to be a deprotonation process, based on the experimental results and theoretical calculations.