Purple Fluorescence Research Articles

Formation Mechanisms and Fluorescence Properties of Carbon Dots in Coal Burning Dust from Coal‐Fired Power Plants

Carbon dots (CDs) show great application potential with their unique and excellent performances. Coal and its derivatives are rich in aromatic ring structure, which is suitable for preparing CDs in microstructure. Coal‐burning dust from coal‐fired power plants can be utilized as a rich resource to separate and extract CDs. It is shown in the results that there are two main possible mechanisms for the formation of CDs in coal‐burning dust. One is the self‐assembly of polycyclic aromatic hydrocarbons contained in coal or produced by incomplete combustion of coal. The other mechanism is that the bridge bonds linking different aromatic structures in coal break, which will form CDs with different functional groups when the coals burn at high temperature. Under violet light excitation at 310–340 nm or red light at 610–640 nm, CDs extracted from coal‐burning dust can emit purple fluorescence around 410 nm. The mechanism of up‐conversion fluorescence emission of CDs is due to a two‐photon absorption process. The recycling of CDs from coal‐burning dust from coal‐fired power plants are not only good to protect environment but will also be helpful for mass production of CDs.

Two Aggregation‐Induced Emission Actives Triphenylamine‐Based Salicylaldimine Compounds for Latent Fingerprints Detection

AbstractTo further explore the candidate materials for latent fingerprints detection, two triphenylamine‐based salicylaldimine compounds containing phenoxazine moiety (TPA‐PXZ) and carbazole unit (TPA‐Cz) were designed and successfully synthesized, respectively. They exhibited intramolecular charge transfer transitions and aggregation‐induced emission properties. Based on quantum chemical calculation results, it was found that compounds TPA‐Cz and TPA‐PXZ had twisted spatial configuration, which were responsible for aggregation‐induced emission. Meanwhile, the morphology of two compounds nano‐aggregates in the THF/water mixtures with 60 % and 80 % water content was tested. To our delight, the developers that prepared by compounds TPA‐Cz and TPA‐PXZ both were used for latent fingerprints detection on the surface of glasses, and they emitted purple fluorescence, as well as the distinct fingerprint imaging could be easily distinguished fingerprint level 1–3 details. We believe that TPA‐Cz and TPA‐PXZ both are the promising candidate for latent fingerprints detection.

Effect of Shikonin on Autophagy and Apoptosis of Human Promyelocytic Leukemia Cells

To explore the effect of shikonin on autophagy and apoptosis of human promyelocytic leukemia cells and its possible mechanism. Human promyelocytic leukemia cells NB4 in the logarithmic growth phase were divided into control group (untreated NB4 cells), shikonin group (0.3 µmol/L shikonin treatment), 740Y-P group (15 µmol/L PI3K/Akt/mTOR pathway activator 740Y-P treatment), shikonin+740Y-P group (0.3 µmol/L shikonin and 15 µmol/L 740Y-P co-treatment), after 24 hours of treatment, the cells were used for subsequent experiments. CCK-8 method was used to detect cell viability, monodansylcadaverine (MDC) staining to detect the aggregation of autophagic vesicles, flow cytometry to detect cell apoptosis, and Western blot to detect the expression of Beclin1, LC3, p62, Bax, cleaved caspase-3, Bcl-2 and PI3K/Akt/mTOR pathway related proteins. Compared with the control group, the purple punctate fluorescence intensity, apoptosis rate, Beclin1, LC3-Ⅱ/LC3-Ⅰ, cleaved caspase-3, and Bax protein expression in NB4 cells were increased in the shikonin group, while OD450 value (24, 48 h) and the expressions of Bcl-2 and p62 proteins were decreased (all P < 0.05). Compared with the control group, the purple punctate fluorescence intensity, apoptosis rate, Beclin1, LC3-Ⅱ/LC3-Ⅰ, cleaved caspase-3, and Bax protein expression in NB4 cells were decreased, while OD450 value (24, 48 h) and the expressions of Bcl-2 and p62 proteins were increased in the 740Y-P group (all P < 0.05). Compared with the shikonin group, the purple punctate fluorescence intensity, apoptosis rate, Beclin1, LC3-Ⅱ/LC3-Ⅰ, cleaved caspase-3, and Bax protein expression in NB4 cells were decreased, while OD450 value (24, 48 h) and the expressions of Bcl-2 and p62 proteins were increased in the shikonin+740Y-P group (all P < 0.05). Compared with the control group, the expression of PI3K/Akt/mTOR pathway related proteins p-PI3K, p-Akt, and p-mTOR in NB4 cells were significantly decreased in the shikonin group, while those in the 740Y-P group were increased (all P < 0.05). Compared with the shikonin group, the expressions of p-PI3K, p-Akt, and p-mTOR proteins in NB4 cells were significantly increased in the shikonin+740Y-P group (all P < 0.05). Shikonin may promote autophagy and apoptosis of NB4 cells by inhibiting PI3K/Akt/mTOR pathway.

A handheld fluorescent platform integrated with a Sm(III)-CdTe quantum dot-based ratiometric nanoprobe for point-of-use determination of phosphate.

Phosphate (Pi) is crucial for various physiological processes and aquatic environments, which emphasizes the need for a simple, on-site sensor to promptly detect Pi for human health and environmental conservation. In this study, we propose a dual-emission ratiometric fluorescence sensor for highly sensitive and visual Pi detection. The sensor employs samarium ions (Sm3+) as a core component, with cadmium telluride quantum dots (CdTe QDs) and ofloxacin (OFL) serving as signal carriers. The CdTe-Sm(III)-OFL nanoprobe emits a purple fluorescence resulting from the red fluorescence of CdTe QDs and the blue-green fluorescence of OFL. The fluorescence of OFL is quenched by Sm3+ through fluorescence resonance energy transfer (FRET). Upon Pi interaction, the FRET process is disrupted due to the competitive Pi-Sm3+ binding, which leads to the fluorescence recovery of OFL while the red fluorescence of CdTe remains steady. This enables the construction of a ratiometric fluorescent sensor for Pi detection, manifesting as a color change from purple to blue. The sensor demonstrated a linear response for Pi detection within the range of 0.1-75 μM, with a low detection limit of 17.0 nM. By utilizing the distinct fluorescence responses of various physiological phosphates and employing chemometrics, this innovative dual-emission sensor accurately distinguishes among different physiological phosphates. Furthermore, a portable lab-on-paper device based on CdTe-Sm(III)-OFL, coupled with a smartphone-integrated mini-device, is developed for swift Pi detection using an ordinary smartphone. Analytical performance validated on environmental and biological samples demonstrates the sensor's excellent robustness and adaptability. This study introduces a pioneering approach to fabricate ratiometric fluorescence sensors and customize portable, cost-effective mini-devices for precise target detection, thus opening avenues for advanced sensing strategies in various applications.

A water-stable Y(III)-MOF as multi-responsive luminescent sensor for high-efficiency detection of Fe3+, Cu2+, and MnO4- ions in aqueous solutions

The effective detection of pollutants in water, such as Fe3+, Cu2+, and MnO4- ions, is critical to human health and environmental protection. Two yttrium-based coordination polymers {[Y(BITA)(H2O)]NO3}n (CP-1) and {[Y(HBTA)(ox)(H2O)]·H2O}n (CP-2) based on a π-conjugated 2,5-di(1H-imidazol-1-yl)terephthalic acid (H2BITA) were successfully prepared and sufficiently characterized. CP-1 exhibits a unique cationic 3D framework with a lvt net, accompanied by the decoration of NO3- anions. Adjacent Y3+ sites are bridged by double syn-syn carboxylate to form [Y2(μ-COO)2]n chains. CP-2 shows a 3D two-fold interpenetrating network with zigzag chains of [Y2(μ-C2O2)]n formed by ancillary oxalate bridging Y3+ ions. The HBTA- linkers propagate the 1D oxalate chains into 3D frameworks. The luminescent properties of CPs were investigated. Both CPs-1 and 2 exhibit purple and green fluorescence in the solid state, respectively. Meanwhile, CP-1 demonstrates excellent luminescent emission together with good chemical stability. Intriguingly, CP-1 exhibits outstanding selective and sensitive detection of cationic Fe3+ and Cu2+ and anionic MnO4- in aqueous solutions through luminescence quenching. In particular, the luminescence intensity could be significantly decreased by existence of MnO4-, which is seldom reported among the Y(III)-based coordination polymers. The quenching mechanism for various ions has been discussed in detail.

A Layered Aluminophosphate [C17H21N2]3[Al3(PO4)4]·5H2O with Fluorescent Property Derived from Carbazolyl-Modified Template.

Designing and innovating organic structure-directing agents is the key to synthesizing novel molecular sieve structures. Herein, we design a novel carbazolyl-modified template and further synthesize a two-dimensional layered aluminophosphate with [C17H21N2]3[Al3(PO4)4]·5H2O (denoted as ZHKU-2). ZHKU-2 is composed of AA-stacked [Al3P4O16]3- layers constructed from alternating AlO4 and PO3(=O) tetrahedrons to form a 4.6.8 network featured by capped six-ring secondary building units. Carbazolyl-templated ZHKU-2 exhibits strong purple fluorescence with a high quantum yield of 25.98%. This work expands aluminophosphate materials of the [Al3P4O16]3- family and provides a view for synthesizing new molecular sieves by exploring the organic luminescence structure-directing agents.

Novel fluorescent sensor for Al3+ based on a bis-tetraphenylimidazole Schiff base

Although some detection methods for Al3+ have been presented, the rapid, simple and in-situ detection on Al3+ with high selectivity and sensitivity was still anticipated. In this work, a “turn-on” and color-changed fluorescence sensor for Al3+ was reported with the high selectivity and low detection limitation. A bis-tetraphenylimidazole Schiff base (bis-TPMS) was prepared by simple “1 + 2” condensation in 80 % yield. It displayed the strong “turn-on” purple fluorescence on sensing Al3+ selectively among various metallic ions and anions. The detection limitation was as low as 1.56 × 10-8 M. The sensing mechanism was deduced as Al3+ was located in the opening cavity composed of HC = N, OH and NH groups. This sensing ability of bis-TPMS for Al3+ was successfully used in test paper, on-site detection for real samples of gastric tablets, indicating the good application prospect in the simple, rapid and in-situ detection for Al3+ in real samples.

Photo-induced multi-color fluorescent hydrogels for optical information coding and encryption

In this study, we proposed a method to prepare multi-color fluorescent hydrogels with polyvinyl alcohol (PVA) as the cross-linking network and 7-(6-carboxylpentoxy)-4-methylcoumarin (CPMC), N-ethoxyhexanoate-3,3-dimethyl-6-nitro-indolinspiropyran (SPCOOH) and 2′,7′-dichlorofluorescein (DCF) were introduced to the system. Due to the hydroxyl group in PVA can form a reversible borate bond with borax, the hydrogel could be combined with each other through this chemical bond, thus hydrogels possess reversible cross-linking property and programmable property. The introduction of CPMC, SPCOOH and DCF into the hydrogel could give the hydrogel different photo-response properties. Under UV light irradiation, PVA-CPMC, PVA-CPMC/DCF, PVA-SPCOOH and PVA/DCF hydrogels could emit blue, cyan, pink purple and green fluorescence respectively. In addition, PVA/DCF and PVA-CPMC/DCF hydrogels could emit green fluorescence under 505 nm light irradiation. Based on the various properties of hydrogels, we respectively demonstrated the application of hydrogels in the fields of two-dimensional information encryption, three-dimensional information encryption, three-dimensional information coding and anti-counterfeiting, which can achieve the expected results. Therefore, multi-color fluorescent hydrogels may have potential applications in information encryption, information coding, flexible display and other fields.

Coral-like, self-assembled, and spatially bounded Ag nano-particles on franzinite zeolite composite sensor toward accurate, synergetic, and ultra-trace sulfadiazine detection

A coral-like Ag@FRA zeolite nanocomposite sensor reveals high sensitivity toward sulfadiazine (SDZ) in a dual detection of fluorescence and electrochemistry. The sensor has been as-synthesized in the hydrothermal condition through a one-pot self-assembly process in which the high crystalline Ag nanoparticles (NPs) are closely arranged and stacked on the nanosized surface cage window of the FRA (Franzinite) zeolite. Strong ultrasound can drive the coral-like composite release Ag nanoparticles whose distribution range mainly from 10 to 12 nm lead to the purple fluorescence in an emission spectrum. In sea water, the fluorescence increases linearly in the SDZ concentration range of 5 × 10−18-5 × 10−10 M. Furthermore, the LOD (limit of detection) reaches 1.4 × 10−22 M by the spatial confinement effect of the coral-liked FRA cage structure in CV (cyclic voltammetry) method at the characteristic potential peak position of 0.1 V vs. SCE. The theoretical calculation also confirms that the FRA cage structure matches well with the SDZ molecules. Further studies indicate the generation of a novel stable composite sensor with high specificity, good recovery and repeatability, which depends on the induction of silver ions upon the artificial synthesis of FRA.

Heat-Resistant Polymers with Intense, Visible Photoluminescence Functionality and Fluorescence Probing Application

Heat-resistant polymers with an intense, visible photoluminescence (PL) functionality are presented. A polybenzoxazole (PBO) containing hexafluoroisopropylidene (HFIP) side groups exhibited an intense purple PL with a quantum yield, ΦPL, of 0.22 (22%), owing to the effectively disturbed concentration quenching (CQ) in the fluorophore units by the bulky HFIP side groups. The chain ends of a wholly cycloaliphatic polyimide (PI), derived from 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA) and 4,4′-methylenebis(cyclohexylamine) (MBCHA), were modified with conjugated monoamines. The PI derived from 2,3,6,7-naphthalenetetracarboxylic dianhydride (2,3,6,7-NTDA) and MBCHA exhibited a very high glass transition temperature (Tg = 376 °C) and purple fluorescence from the S1(π,π*) state. However, its ΦPL value was lower than expected. A pronounced effect of fluorophore dilution using CBDA on the PL enhancement was observed. This is closely related to the planar structure of the 2,3,6,7-NTDA-based diimide units. By contrast, the counterpart using an 2,3,6,7-NTDA isomer, 1,4,5,8-NTDA, was virtually non-fluorescent, despite its sufficient dilution using CBDA. The PI film obtained using 3,3″,4,4″-p-terphenyltetracarboxylic dianhydride (TPDA) with a non-coplanar structure and MBCHA exhibited an intense blue fluorescence spectrum (ΦPL = 0.26) peaking at 434 nm. The dilution approach using CBDA enhanced its fluorescence up to a high ΦPL value of 0.41. Even when TPDA was combined with an aromatic diamine, 2,2′-bis(trifluoromethyl)benzidine (TFMB), the intense blue fluorescence was observed without charge-transfer fluorescence. A semi-cycloaliphatic PI derived from TFMB and a novel cycloaliphatic tetracarboxylic dianhydride, which was obtained from a hydrogenated trimellitic anhydride derivative and 4,4′-biphenol, was used as another host polymer for 9,10-bis(4-aminophenyl)anthracene (BAPA). The BAPA-incorporating PI film resulted in a significant PL enhancement with a considerably high ΦPL of 0.48. This PI film also had a relatively high Tg (265 °C). A reactive dye, N,N′-bis[4-(4-amino-3-methylbenzyl)-2-methylphenyl]-3,4,9,10-perylenetetracarboxydiimide, was harnessed as a fluorescence probe to explore transamidation between polyimide precursors in solution.

One-pot solvothermal preparation of triple-emission N, Cl doped carbon quantum dots from waste traditional Chinese medicines as a fluorescent sensor for sensing water and Cr (Ⅵ)

In this research, N, Cl doped carbon quantum dots (CQDs) with triple-fluorescence centers was prepared by one-pot solvothermal method from waste traditional Chinese medicines as the raw material. The obtained N, Cl doped CQDs showed purple, yellow and red fluorescence under the 326, 380 and 578 nm excitation, respectively, of which red fluorescence was induced by the increase of concentrations and sensed rapidly water contents in 30–100% range with a limited of detection (LOD) of 0.65%. The obtained CQDs was applied for sensing Cr (Ⅵ) by triple channels, which exhibited the high selectivity and sensitivity for Cr (Ⅵ) with the LOD of 0.28, 0.87 and 0.90 μM, respectively. And its derivative materials exhibited the good linear range with 10–100 μM and 5–250 μM taking purple fluorescence as the response signal, respectively. The recoveries of N, Cl doped CQDs in tap water and sludge were in 93–110% range, suggesting a feasible avenue for accurate and rapid sensing of Cr (Ⅵ).

β-Cyclodextrin derived full-spectrum fluorescent carbon dots: The formation process investigation and biological applications

Carbon dots (CDs), a new building unit, have been revolutionizing the fields of biomedicine, bioimaging, and optoelectronics with their excellent physical, chemical, and biological properties. However, the difficulty of preparing excitation-dependent full-spectrum fluorescent CDs has seriously hindered their further research in fluorescence emission mechanisms and biomedicine. Here, we report full-spectrum fluorescent CDs that exhibit controlled emission changes from purple (380 nm) to red (613 nm) at room temperature by changing the excitation wavelength, and the excitation dependence was closely related to the regulation of sp2 and sp3 hybrid carbon structures by β-cyclodextrin-related groups. In addition, by regulating the content of β-cyclodextrin, the optimal quantum yields of full-spectrum fluorescent CDs were 8.97%, 8.35%, 7.90%, 9.69% and 17.4% at the excitation wavelengths of 340, 350, 390, 410 and 540 nm, respectively. Due to their excellent biocompatibility and color tunability, full-spectrum fluorescent CDs emitted bright and steady purple, blue, green, yellow, and red fluorescence in MCF-7 cells. Moreover, we optimized the imaging conditions of CDs and mitochondrial-specific dyes; and realized the mitochondrial-targeted co-localization imaging of purple, blue and green fluorescence. After that, we also explored the effect of full-spectrum fluorescent CDs in vivo fluorescence imaging through the intratumorally, subcutaneously, and caudal vein, and found that full-spectrum fluorescent CDs had good fluorescence imaging ability in vivo.

Multifunctional Eu(III)-modified HOFs: roxarsone and aristolochic acid carcinogen monitoring and latent fingerprint identification based on artificial intelligence.

The exploration of multifunctional materials and intelligent technologies used for fluorescence sensing and latent fingerprint (LFP) identification is a research hotspot of material science. In this study, an emerging crystalline luminescent material, Eu3+-functionalized hydrogen-bonded organic framework (Eu@HOF-BTB, Eu@1), is fabricated successfully. Eu@1 can emit purple red fluorescence with a high photoluminescence quantum yield of 36.82%. Combined with artificial intelligence (AI) algorithms including support vector machine, principal component analysis, and hierarchical clustering analysis, Eu@1 as a sensor can concurrently distinguish two carcinogens, roxarsone and aristolochic acid, based on different mechanisms. The sensing process exhibits high selectivity, high efficiency, and excellent anti-interference. Meanwhile, Eu@1 is also an excellent eikonogen for LFP identification with high-resolution and high-contrast. Based on an automatic fingerprint identification system, the simultaneous differentiation of two fingerprint images is achieved. Moreover, a simulation experiment of criminal arrest is conducted. By virtue of the Alexnet-based fingerprint analysis platform of AI, unknown LFPs can be compared with a database to identify the criminal within one second with over 90% recognition accuracy. With AI technology, HOFs are applied for the first time in the LFP identification field, which provides a new material and solution for investigators to track criminal clues and handle cases efficiently.

Synthesis of carbon nanoblocks and carbon nanorods by Tween-80@NaCl

• A method for the synthesis of carbon nanoblocks and carbon nanorods exploiting the strategy of self-assembled ordered aggregates @ concentrated salt was investigated. • The morphology (size and shape) and specific optical (fluorescence) properties of the synthesized Tween-80@NaCl carbon nanoparticles can be systematically tuned on demand. • Such method may be adopted as a general method for the preparation of various carbon nanostructures. Carbon nanomaterials are very versatile, but the tunable preparation of their morphology and emission colors is still very challenging. Herein, we present a simple self-assembly method for the preparation of tunable carbon nano (Tween-80@NaCl), where the key tunable parameter is the concentration. More specifically, the structural and optical properties of carbon nanomaterials can be controlled by modulating the concentration of surfactants. It is worth mentioning that salt plays an important role in separating the micelle structure and protecting the micelle morphology. The samples were characterized by Raman spectroscopy and x-ray diffraction to determine the microcrystalline structure and crystal size. The evolution of the micellar structure was established by transmission electron microscopy analysis of the transformation of the Tween-80@NaCl structure. The continuous adjustment of surfactant concentration leads to a change in micelle morphology, like from large-sized blocks to small-sized rods. In addition, carbon nanoparticles with typical fluorescence properties can be obtained by simply changing the surfactant concentration and can easily change from purple fluorescence to dark blue. Notably, this simple strategy of separating first and then carbonizing provides inspiration for future structural design of carbon nanomaterials.

Study on Fluorescence Properties of Green-Blue Apatite

The fluorescence phenomenon of apatite is an important feature. In this paper, three apatites with uniform transition from green to blue were selected, and the fluorescence color characteristics of the samples were observed under UV fluorescent lamp and DiamondView. With 3D fluorescence technology, combined with LA-ICP-MS, this paper aims to comprehensively test the fluorescence phenomenon of apatite to explore the relationship between apatite fluorescence and elements and analyze the fluorescence color characteristics. With the experiments mentioned above, this paper explores the fluorescent color characteristics of gemstones and their influencing factors to improve the color system of apatite. UV and DiamondView experiments show that with the change from green to blue, apatites show weak purple–red to strong pink–purple fluorescence. The 3D fluorescence test shows that the samples have two notable fluorescence emission peaks: (1) The fluorescence peak group composed of the double fluorescence peaks around 600 nm is generated by the excitation light source at 450 and 470 nm and a weaker fluorescence peak generated by the excitation at 400 nm; (2) The fluorescence emission peak of the sample gradually becomes prominent and the intensity increases significantly near the areas where the excitation wavelength is 280–330 nm and where the emission wavelength is 380 nm. According to the LA-ICP-MS test combined with the element properties, the fluorescence peak group (1) is mainly affected by Mn2+, Sm3+, and Pr3+, which emit orange fluorescence. The fluorescence emission peak (2) is caused by Ce3+, Eu3+, Dy3+, and Tb3+, which emit purple fluorescence. The mixing of the two fluorescent colors results in violet–pink fluorescence.

A deep ultraviolet transparent birefringent monofluorophosphate: Cd 2.5 (NH 4 ) 2 (PO 3 F) 3 Cl ⋅ 2H 2 O

Herein, we report a new monoclinic, Cd2.5(NH4)2(PO3F)3Cl ⋅ 2H2O (CNPFC, cadmium ammonium monofluorophosphate chloride dihydrate), featuring a [Cd3P2O12ClF2]∞ double-layered structure. CNPFC is DUV transparent, exhibits a quite large laser induced damage threshold (1.33×KDP) and emits a purple fluorescence at 410 nm. On an as-synthesized (100)-single crystal plane, the Δnobv.(100)=nc–nb=0.012 is measured at 546 nm, which is consistent with the theoretical calculated 0.017. The birefringence of CNPFC is theoretically calculated to be Δncal.=nZ–nX=0.035. We further demonstrate that the diverse coordination environments and inter-unit linkages of the Cd-centered polyhedra as well as different hydrogen bonding interactions give rise to an interesting structural relationship among three related compounds.

Triple-emission nitrogen and boron co-doped carbon quantum dots from lignin: Highly fluorescent sensing platform for detection of hexavalent chromium ions

Considering that hexavalent chromium ions (Cr6+) with high toxicity poses a huge threat to human health and the ecological environment, constructing a rapid and accurate sensing platform is of great significance in detecting the toxic substance. The novel nitrogen and boron co-doped carbon quantum dots (N, B-CQDs) from lignin are synthesized as fluorescent sensors for the detection of Cr6+. The synthetic processes involve the acid hydrolysis step followed by the hydrothermal treatment step. Lignin is firstly depolymerized by cleaving ether bonds in the acidolysis, and N, B-CQDs are consequently formed by the aromatic re-fusion of lignin nanoparticles in the hydrothermal process. The lignin-derived N, B-CQDs show triple emission of purple, blue and green fluorescence under the excitation of 300, 330, and 490 nm, respectively. The triple-emission N, B-CQDs are applied for the triple-channel detection of Cr6+, which exhibit highly sensitive and selective fluorescence quenching for Cr6+ with good linearity (R2 ≤ 0.996) and very low limit of detection as 0.054, 0.049, and 0.077 μM under the excitation of 300, 330 and 490 nm, respectively. The utilization of renewable lignin as CQDs-based fluorescent sensors opens a new avenue for the rapid and accurate detection of Cr6+ through a multichannel sensing platform.

Driving Nonlinear Optical Activity with Dipolar 2-Aminopyrimidinium Cations in (C4H6N3)+(H2PO3)−

Organic–inorganic hybrid nonlinear optical (NLO) crystals have been attracting increasing attention because of their unique ability to combine the structural diversity of the organic moiety and the high stability of the inorganic moiety. However, organic NLO genes are rare. Herein, a new organic NLO material gene, the 2-aminopyrimidinium cation (C4H6N3)+ ((2AP)+), is reported, which constructs a novel organic–inorganic hybrid (C4H6N3)+(H2PO3)− (2APP) that exhibits excellent NLO properties and thermal stability, e.g., strong second-harmonic generation (SHG) intensity (2 × KDP), large birefringence (0.225 at 589.3 nm), high laser-induced-damage threshold (1.7 × KDP), and one of the highest thermal stabilities among the metal-free-(2AP)+-containing compounds. Our first-principles theoretical studies confirm the dominant contribution of (2AP)+ to optical properties. The inorganic phosphite anions well separate the (2AP)+ cations to successfully eliminate the unwanted centrosymmetric trap that is induced by the dipole–dipole interactions between (2AP)+ cations. Furthermore, the unique layered structure decorated by the uniformly oriented individual (2AP)+ chromophores, dramatically enhances the quantum yield of purple fluorescence (Φ = 30.6%), which is 3 orders of magnitude higher than that of pure 2AP and its derivatives.

Preparation and characterization of yellow waterborne polyurethane with 2,6-diaminoanthraquinone structure

Poly (2-methyl-1,3-propylene glycol-adipic acid) ester diol (PMA-1000), 2,2-dihydroxymethyl propionic acid (DMPA), toluene diisocyanate (TDI), 1,4-butanediol (BDO), 2,6-diaminoanthraquinone (DAAQ) were used as raw materials, triethylamine (TEA) as neutralizer, and yellow waterborne polyurethane dye (DAAQ-WPU) containing DAAQ was obtained after emulsification. The structure and properties of the product were characterized by infrared spectroscopy, fluorescence spectrophotometer, laser particle size analyzer, spectrophotometer and color fastness tester. The results show that, DAAQ anthraquinone structure is connected to the water-based polyurethane chain, DAAQ-WPU is synthesized, and its emulsion has purple fluorescence at 300–350 nm band. With the increase of DAAQ content, the particle size of DAAQ-WPU emulsion increases from 69.7 nm to 104.9 nm, the b* value of film increases from 10.4 to 45.39, and the yellow color deepens gradually. DAAQ-WPU has good color fastness to cotton cloth, and its color fastness to rubbing, water stain and soaping is 4–5 grade.

A study on multifunctional protein fibre with UV protection, moth repellency and antibacterial properties using ESIPT core containing benzimidazole and benzothiazole based functional acid azo dyes

Water soluble fluorescent acid azo dyes with benzimidazole and benzothiazole component having excited state intramolecular proton transfer (ESIPT) core were synthesised by diazo coupling. The structure of the dyes were analysed and confirmed by Fourier Transform Infrared – spectroscopy (FT-IR), elemental analysis, 1H NMR and 13C NMR analysis. Absorption and emission characteristics of the dyes were studied in different polarity solvents shown bathochromic (red) shift as solvent polarity increases. Wool and silk fabric dyed with synthesised dyes displayed high exhaustion, uniform dyeing and good wet fastness properties. The dyed substrate showed green and purple fluorescence under UV light (366 ​nm) along with UV protection. Dyed wool fabric was also assessed for antibacterial activity by calculation of bacterial reduction Staphylococcus Auerus (Gram positive), Klebsiella Pneumonia (Gram negative) bacteria. The dyed wool were also examined for the resistivity against insect pests Anthrenus Flavipies (Le Conte) by calculation of the fabric weight loss, Mortality of moth and visible assessment of fabric attacked by moth after 14 days in given conditions. Consequently, it was demonstrated that wool fabric dyed with Benzimidazole and benzothiazole based acid dyes had various functionalities, such as UV protection, antibacterial activity and mild moth repellency.