Changes In Emission Intensity Research Articles

Prediction of Suitable Habitat of Alien Invasive Plant Ambrosia trifida in Northeast China under Various Climatic Scenarios

Ambrosia trifida is an invasive alien plant species, which has very high reproductive and environmental adaptability. Through strong resource acquisition ability and allelopathy, it could inhibit the growth and reproduction of surrounding plants and destroy the stability of an invasive ecosystem. It is very important to predict the change of suitable distribution area of A. trifida with climate change before implementing scientific control measures. Based on 106 A. trifida distribution data and 14 points of environmental data, the optimal parameter combination (RM = 0.1, FC = LQ) was obtained using the MaxEnt (version 3.4.1) model optimized by Kuenm package, and thus the potential suitable areas of A. trifida in Northeast China under three different climate scenarios (RCP2.6, RCP4.5, RCP8.5) with different emission intensities in the future (2050, 2070) were predicted. The changes of A. trifida suitable area in Northeast China under three climate scenarios were compared, and the relationship between the change of suitable area and emission intensity was analyzed. In general, the suitable area of A. trifida in Northeast China will expand gradually in the future, and the area of its highly suitable area will also increase with the increasing emission intensity, which is unfavorable to the control of A. trifida.

Influence of FRET, charge separation, and density of defect states on the improvement of UV light-driven photocatalytic activity of PMMA capped ZnO nanomaterials

This study employs oxidative polymerization, co-precipitation, and ex-situ surface capping techniques to fabricate pristine PMMA, ZnO, and PMMA-capped ZnO specimens with varying PMMA concentrations. X-ray diffraction reveals reduced directional growth of ZnO, while Fourier transform infrared spectroscopy confirms PMMA chain bonding with ZnO in PMMA-capped specimens. Scanning electron microscopy illustrates decreased average length and thickness of ZnO nanoplates post-surface modification, indicating a robust interaction between PMMA and ZnO. X-ray photoelectron spectroscopy identifies suppressed defects, including zinc interstitials and oxygen vacancies, affirming ZnO surface capping by PMMA. Absorption spectra display a blue shift in band-edge or increased bandgap, attributed to the combined effects of band alignment offset and reduced oxygen vacancy states. Luminescence spectra show gradual quenching linked to PMMA content increase, with defect-related emission suppression attributed to ZnO surface capping. UV emission suppression is ascribed to donor concentration-dependent Förster resonance energy transfer (FRET) from PMMA to ZnO. Photocatalytic tests reveal enhanced efficiency in PMMA-capped ZnO catalysts attributed to synergies involving charge separation, bulk recombination centers, oxygen vacancy states, and FRET. Efficiency improves with higher PMMA content, aligning with changes in emission intensity. The study demonstrates emission intensities' tunability through surface capping and donor concentration-dependent FRET, ultimately influencing degradation efficiency.

Innovative surfactant-free synthesis of core-shell SiO2/ZnO particles: rapid ultrasonication and photocatalytic inhibition.

This study demonstrates the preparation of SiO2/ZnO core-shell nanoparticles with controllable shell size and their optical properties. A facile ultrasonication method was utilized to prepare the core-shell particles in the absence of surfactant materials. The synthesis duration was 75% shorter than that required for the common sol-gel method, which favours its potential applicability in the future for mass production. Tetraethyl orthosilicate (TEOS) was used as the silica source, while the core material was prepared using zinc acetate dihydrate. The outer shell size could easily be controlled by changing the molar ratio of silica from 0.25 to 1.00. The experimental results show that increasing the silica ratio was effective in suppressing the self-agglomeration of ZnO and, further, in obtaining agglomeration-free particles. The investigation of the photoluminescence (PL) properties of nanometre-sized ZnO revealed several emission peaks in the ultraviolet (UV) wavelength range, indicating variations in bandgap energy. This did not appear in the spectrum of micrometre-sized ZnO particles. The core-shell particles produced with higher amounts of silica showed higher UV-A and UV-B absorption. In addition, the presence of silica reduced the photocatalytic activity of ZnO by 65% and reduced the PL intensity. The obtained emission peaks, intensity changes, and spectral characteristics open new avenues for further research on tailoring the properties of SiO2/ZnO core-shell structures for specific technological advancements. These advancements hold promising applications in UV attenuation materials, LED technologies, lenses, and solar cells within the realm of optical devices.

Responsive organic room-temperature phosphorescence materials for spatial-time-resolved anti-counterfeiting

Stimulus-responsive room-temperature phosphorescence (RTP) materials have gained significant attention for their important optoelectronic application prospects. However, the fabrication strategy and underlying mechanism of stimulus-responsive RTP materials remain less explored. Herein, we present a reliable strategy for achieving pH-responsive RTP materials by integrating poly(vinyl alcohol) (PVA) with carboxylic acid or amino group functionalized terpyridine (Tpy) derivatives. The resulting Tpy derivatives-based RTP materials displayed reversible changes in emission color, intensity, and lifetime of both prompt and delayed emission. Notably, the RTP emission undergoes a significant diminish upon exposure to acid due to the protonation of Tpy units. Taking advantage of the decent RTP emission and pH-responsiveness of these RTP films, a spatial-time-resolved anti-counterfeiting application is demonstrated as a proof-of-concept for largely enhancing the security level. This study not only provides new prospects for developing smart RTP materials but also promotes the advancement of optical anti-counterfeiting applications.

Tunable Anti‐Thermal Quenching Luminescence of Eu3+‐Doped Metal‐Organic Framework and Temperature‐Dependent Photonic Coding

AbstractApplications of luminescence at high temperature such as high‐power lighting, lasing, thermophotovoltaics, and photonic coding, are severely prevented due to the notorious thermal quenching (TQ). Although anti‐TQ luminescence (anti‐TQL) is reported using highly oxygen‐coordinated solid‐state oxide as host in virtue of the rigid skeleton that resists lattice vibration at elevated temperatures, it is meaningful to extend anti‐TQL to other hosts. Herein, taking advantage of the ligand‐metal antenna effect and the negative thermal expansion feature of Eu3+ doped MIL‐68‐In (MIL‐68‐In/xEu), adjustable anti‐TQL is realized for the first time, that is, anti‐TQ, zero‐TQ, and TQ at x = 5%, 10%, and 50%, respectively. Therefore, except for added novel mechanisms, this work has also expanded the hosts available for high‐temperature luminescence and enabled advanced photonic coding in terms of facial synthesis, rich information, and visual changes of emission intensity instead of device‐dependent analogous.

Temperature sensing performance of M2La8(SiO4)6O2:Ce3+(M=Ca, Sr, Ba) based on fluorescence intensity ratio of dual emission centers in different coordination environments

Rare earth doped luminescent sensing materials as non-contact thermometers have attracted extensive research interests due to their wide applications in areas like military, medical care, aerospace, etc. How to expand the working temperature range and improve the sensitivity has become the focus. In this work, we synthesized a series of apatite-structured luminescent temperature sensors M2La7.9Ce0.1(SiO4)6O2 (M = Ca, Sr, Ba) via isomorphic substitution. By monitoring the differential changes of emission intensities from Ce3+ at the 7-coordinate and 9-coordinate site respectively when temperature varies, the real-time temperature can be determined. These materials were proven to possess the maximum absolute sensitivity up to 0.825 × 10−3 K−1, 2.63 × 10−3 K−1 and 4.33 × 10−3 K−1, respectively. Meanwhile interesting regular patterns were observed for their temperature sensitivities with the substitution of Ca, Sr and Ba. Furthermore, through studying the temperature sensitivity of Ba2La8(SiO4)6O2:xCe3+ samples with different concentrations, it was found that when the Ce3+ content was at the optimal doping concentration of 0.7, the absolute sensitivity of the sample reached 14.64 × 10−3 K−1 at 573 K. This finding has opened up a new avenue for designing fluorescent temperature sensors.

Analysis of energy policy reform in Iran: Energy and emission intensity changes

The Subsidized energy system of Iran, with its high financial burden, failed to achieve its intended economic goals, resulting in increased energy consumption and pollutant emissions. Energy product subsidies in Iran are among the highest in the world and have important implications for developing countries. This study examines the impact of subsidy removal policy on energy and emission intensities using a Dynamic Computable General Equilibrium model. The findings reveal that after subsidy removal, total output experiences an annual growth of around 1.5%, with output composition changes mainly favoring agriculture and services that are less energy dependent. However, prices soar by at least 10% owing to the higher costs of energy products. The decreasing trend in energy intensity after subsidy reform is accompanied by a decrease in emission intensity. Higher prices of energy after subsidy removal and the corresponding improvement in the efficiency of energy consumption lead to lower emission intensity.

Research on bi‐layer low carbon scheduling strategy for source‐load collaborative optimization based on node carbon emission intensity

AbstractTo accurately calculate the carbon emission of integrated energy system (IES), and fully explore the potential for load side on carbon emission reduction, this paper proposes a method of guiding load to participate in demand response based on node carbon emission intensity, and constructs a bi‐layer low‐carbon scheduling model for source‐load collaborative optimization. First, the carbon flow calculation model of IES in the total process is established, such as source, network, load, and storage. It can depict the carbon emission characteristics of energy conversion equipment and energy storage devices. The principle of proportional sharing is used to track carbon emission flows, the changes in carbon emission intensity at each node is perceived from a spatiotemporal perspective. Second, carbon flow analysis is incorporated into the load demand response mechanism, and a carbon emission model for load aggregator (LA) after demand response is established based on the node carbon emission intensity. Third, a bi‐layer low‐carbon scheduling model is constructed, which considers the source‐load collaborative optimization. The upper layer is the optimal economic dispatch of IES operators, while the lower layer is the optimal economic dispatch of LAs. Finally, the effectiveness of the proposed method is verified using the system as an example, such as improved 14‐node power grid, 6‐node heating network, and 6‐node nature gas network.

Global economic structure transition boosts PM2.5-related human health impact in Belt and Road Initiative

The Belt and Road Initiative (BRI) is an open platform for international cooperation proposed by China to promote common global development and prosperity. The BRI can promote the optimal allocation of resources and promote in-depth cooperation in international trade. Meanwhile, it can establish a green supply chain cooperation network to help BRI countries achieve green transformation. BRI has made a notable contribution to the rapid growth of cross-border trade. However, it has also brought environmental impacts. Given that little attention has been paid to the trade-embodied particulate matter 2.5 related human health impacts (PM2.5-HHI) throughout the BRI, this study accounts for and traces the embodied PM2.5-HHI flows between the BRI countries and non-Belt and Road Initiative (non-BRI) countries. Moreover, this study also uncovers the critical socioeconomic drivers of PM2.5-HHI changes in BRI countries during 1990–2015, based on the multi-regional input-output based structural decomposition analysis (MRIO-SDA). Results show that, firstly, BRI countries had significantly increased their economic added value by exporting products to the non-BRI countries. They also have brought PM2.5-HHI to themselves. Secondly, the final demand of BRI countries was the largest potential driving force of PM2.5-HHI of BRI countries. Thirdly, the emission intensity change of BRI is the key socioeconomic factor for reducing PM2.5-HHI. While per capita final demand level change of BRI and production structure change of non-BRI are the key socioeconomic factors for increasing PM2.5-HHI. The study's findings on the one hand can help reduce the PM2.5-HHI and impacts of environmental pollution of BRI countries from a global perspective by providing scientific support. On the other hand, they can help provide relevant policy recommendations for the green transformation of BRI and the construction of green BRI.

Analysis of hydrogen in a hydrogenated, 3D-printed Ti–6Al–4V alloy by glow discharge optical emission spectroscopy: sample heating effects

In the analysis of hydrogen in a hydrogenated, 3D-printed Ti–6Al–4V alloy by GDOES, hydrogen diffuses from the depth due to sample heating, enters the plasma and affects the signal response. A model of heat conduction within the sample is presented.

Resonant interaction between runaway electrons and the toroidal magnetic field ripple in TCV

This work explains the anomalously high runaway electron (RE) pitch angles inferred in the flat-top of dedicated Tokamak à Configuration Variable (TCV) experiments. Kinetic modelling shows that the resonant interaction between the gyromotion of the electrons and the toroidal magnetic field ripple will give rise to strong pitch angle scattering in TCV. The resulting increase in synchrotron radiation power losses acts as a RE energy barrier. These observations are tested experimentally by a magnetic field ramp-down, which gradually reduces the resonant parallel momentum at which the REs interact with the ripple. Resulting changes in synchrotron emission geometry and intensity are observed using three multi-spectral camera imaging systems, viewing the RE beam at distinct spatial angles in multiple wavelength ranges. Experimental reconstructions of the RE distribution in momentum- and real-space are consistent with kinetic model predictions.

Long-term variation, solubility and transport pathway of PM2.5-bound iron in a megacity of northern China

Although particulate Fe has a significant impact on human health, atmospheric chemical reactions, air quality, climate change, and ecosystems, there is a lack of long-term continuous hourly observation on particulate Fe in the megacity of Beijing, limiting research on these issues. To address this gap, this study continuously measured hourly concentrations of Fe in PM2.5 from October 2018 to October 2022 in Beijing. The results indicate an overall decline in Fe concentrations, consistent with previous studies in Beijing. This decline can be attributed to multiple factors, such as reduced coal consumption, restrictions on biomass burning, increased use of clean energy, advanced technologies for industrial emission reduction, and efforts to control fugitive dust. Seasonal variations in Fe concentrations were similar across the various years, with higher mean concentrations in spring, fall, and winter, and lower levels in summer. Daily variations in PM2.5-bound Fe concentrations exhibited two peaks, influenced by changes in emission intensity and the evolution of the planetary boundary layer. The solubility of PM2.5-bound Fe exhibited a wide range, varying from 4 % to 95 %, surpassing previously reported source-specific values. This variability can be attributed to acid dissolution effects and complexation behaviors. Nonparametric wind regression analysis identified distinct hotspots (higher concentrations) in the northwest wind sector at wind speeds of approximately 5–15 km/h, which are associated with blowing dust and dust storms. Additionally, the potential source contribution function analysis identified high-potential source areas were precisely located in the northwestern, western, and southern regions of Beijing, rather than primarily in the southern areas recorded in a previous study. This research provides valuable insights for studying the health effects and migration and transformation of nutrient elements, particularly particulate Fe, in Beijing.

Highly sensitive and selective ratiometric fluorescent and visual detection of Cu2+ based on the hydroxytyrosol–naphthoresorcin–quantum dots sensing platform

Fluorescence-based visual analysis has attracted considerable attention in on-site detection owing to their distinct color gradient changes, easy operation and high sensitivity. In this work, we construct an exceptionally simple dual-emission ratio fluorescence sensor through the synergy of hydroxytyrosol (HYT), naphthoresorcin (NR) and ZnCdSe/ZnS quantum dots (QDs), namely HYT–NR–QD, for the fluorescent and visual detection of Cu2+. The design of ratiometric nanosensor is based on our new finding that Cu2+ can catalyze the reaction between HYT and NR to produce a cyan-emitting fluorophore (emission: 480 nm), and the copper species existed in the form of Cu+ and Cu2+ in reaction system. After adding QDs (emission: 605 nm), the free Cu+, Cu2+ and the resulting fluorophore in this system caused a great reduction in the FL intensity of QDs, due to the rapid cation exchange reaction between QDs and Cu2+/Cu+ as well as the inner filter effect between QDs and the resulting fluorophore. Overall, Cu2+ induced emission intensity changes at 480 and 605 nm leads to a distinct color change from red to cyan. A ratiometric fluorescence Cu2+ sensor with a lowest concentration of 3.42 nM was developed. Furthermore, the concentration of Cu2+ can be conveniently reflected with a smartphone application by identifying the RGB value. Moreover, the method proposed by us can be explored for Cu2+ determination in environmental water samples with a satisfying result, providing a novel, simple-operating and on-site detection of Cu2+ in water samples.

Co-doping effect of Ce ions on Eu ion-doped Sr2SnO4 in terms of emission color tunability and intensity modulation

We investigated the co-doping effect of Ce3+ and Eu3+ ions on the visible emission of the single-layered perovskite Sr2SnO4. The Ce3+ single-doped Sr2SnO4 showed a sizable feature at approximately 260 nm in the photoluminescence excitation spectra and a broad peak at approximately 400 nm in the photoluminescence spectra. These peaks were attributed to the 4f–5d transitions of Ce3+. In the Ce3+ and Eu3+ co-doped samples, as the concentration of Ce3+ increased, the emission intensity of Eu3+ increased drastically with near-ultraviolet excitation due to the energy transfer from Ce3+ to Eu3+. Because of the changes in the relative emission intensities of the two ions, the colors emitted by phosphor were tuned from blue/orange to red. We also discussed the effect of Ce3+ doping on the photochromic behavior of Eu3+-doped Sr2SnO4, together with luminescence modulation.

Development of ratiometric fluorescent probes based on peptides for sensing Pb2+ in aquatic environments and human serum.

The detection of Pb2+ ions in aquatic environments and biofluid samples is crucial for assessment of human health. Herein, we synthesized two fluorescent probes (1 and 2) consisting of the peptide receptor for Pb2+ and a benzothiazolyl-cyanovinylene fluorophore that exhibited excimer-like emission when it aggregated. The peptide-based probes sensitively detected Pb2+ in purely aqueous solution (1% DMF) through ratiometric fluorescent response with a decrease in monomer emission at 520nm and an increase in excimer emission at 570nm. Specially, probe 2 showed remarkable detection features such as high selectivity for Pb2+over 15 metal ions, high binding affinity (Kd=5.83×10-7 M) for Pb2+, significant emission intensity changes, low detection limit (3.8nM) of Pb2+, high water solubility, and visible light excitation (450nm). Probe 2 was successfully used to quantify nanomolar concentration (0∼800nM) of Pb2+ in real water samples (ground water and tap water). Specially, 2 was successfully applied for the quantification of Pb2+ in human serum by combination of microwave-assisted human serum digestion and filtration of digested serum by anion exchange cartridge. We clearly investigated the binding mode of 2 with Pb2+ using 1H NMR, IR spectroscopy, pH titration, confocal microscopy, and size analysis. The peptide-based fluorescent probe might have great application potential for sensing Pb2+ in aquatic environments and biofluid samples.

Hetero-Aggregation-Induced Tunable Emission in Multicomponent Crystals

Crystal engineering is a green and convenient approach to designing desirable materials through rational manipulation of intermolecular interactions. We have reported the lesser reported sulfonate–pyridinium intermolecular interaction for the design and synthesis of organic co-crystals with improved features. Here in we report the utilization of the interaction to tune the solid-state luminescence of organic precursor naphthalene disulfonic acid (NDSA-2H). Organic salts of NDSA-2H are synthesized and characterized with three isostructural bipyridyl co-formers: 4-phenylpyridine (4-PhPy), 2-phenylpyridine (2-PhPy) and 2,2′-bipyridine (2,2-bpy). Structural investigation validates aggregation of organic acid and base co-formers through sulfonate–pyridinium synthon and proton transfer between them. Compared to NDSA-2H, the molecular salts [(4-PhPy-H)2+(NDSA)2–·2H2O] (1) and [(2,2-BPY-2H)2+(NDSA)2–] (3) undergo a blue and red shift, respectively, while solid-state emission of [(2-PhPy-H)2+(NDSA)2–] (2) remains unaltered. This solid-state emission tuning is attributed to the different modes of crystal packing and arises from monomer emissions in 1 and 2 and excimer emission in 3. 3 also exhibits a relatively longer lifetime of 20.7 ns while 2 exhibits better quantum yields (ϕ = 22.7). Solution-phase photophysical behavior has been investigated for representative co-crystal system 3, after validation of its solution-phase integrity. 3 undergoes a hetero-aggregation-induced tunable emission (HAITE) phenomenon in the water–acetone system to exhibit maximum emission intensity at 90% volume fraction of acetone, which is further validated by the diffuse light scattering (DLS) and scanning electron microscopy (SEM) studies. 3 also exhibits solvatochromism in terms of emission intensity change with the nature of the solvent, being brightest in methanol (ϕ = 29.3) and very dim in water (ϕ = 10.1).

Superior triethylamine sensing platform based on MOF activated by carbon dots for photoelectric dual-mode in biphasic system

Multimode sensors are required to enable detect of hazardous substances in different media. A sensing platform based on metal organic frameworks (MOF) and its derivatives was established to detect triethylamine (TEA) gas and TEA aqueous solution in the range of 1–100 ppm. The carbon dots (CDs) were selected as the light-energy conversion module to improve greatly the photoelectric performance of sensors. On the one hand, the dual-emission ratio type fluorescent sensor was built by CDs and MOF. The CDs@ZIF-8(In) showed excellent fluorescence emission enhancement at 440 nm and 610 nm in a dose-dependent manner when TEA was added. The change of fluorescence emission intensity of CDs@ZIF-8(In) sensor for TEA in water was at least 3 times than that of other volatile organic compounds, and its detection limit reached 1 ppm. On the other hand, the gas sensor based on MOF derivatives modified by CDs (CDs@DZIF-8(In)) displayed 3.5 times signal response than pure DZIF-8(In), reaching 374.6 to 100 ppm TEA. Moreover, the optimal operating temperature of CDs@DZIF-8(In) sensor was 40 ℃ lower than that of DZIF-8(In) sensor. The excellent fluorescence and electron transfer properties of CDs may play a key role in the design and modification of various types of sensors.

N-aryl-4-amino-1,8-naphthalimide Tröger's bases-based internal charge transfer (ICT) fluorescence ‘turn-on’ chemosensors for volatile organic amines

The design of reliable sensor systems for quick sensing and monitoring the trace concentrations of volatile organic compounds (VOCs) has been a topical area of research in recent years due to their serious menace to living systems and environmental hazardousness. In this article, we report two unique ‘cleft-shaped’ N-aryl-4-amino-1,8-naphthalimide derived Tröger's bases (TBNap-Ph and TBNap-Es) as efficient, fast fluorescence sensors for discriminative sensing of volatile organic amines (VOAs). The fluorescence titration studies using TBNap-Ph and TBNap-Es demonstrated discriminative fluorescence sensing responses for VOAs with high selectivity for benzylamine detection. The initial emission intensity of TBNap-Ph and TBNap-Es was enhanced drastically upon the addition of benzylamine. However, similar titration studies using other VOAs such as n-propylamine, n-butylamine, diethylamine, isopropylamine, 3-dimethylamino-1-propylamine, triethylamine, and ethanolamine elicited poor to negligible changes in the fluorescence emission intensity. The selective ‘turn-on’ fluorescence sensing of benzylamine was also reflected by sharp color changes and these sensors can be used to detect benzylamine at the parts-per-millions (ppm) level of sensitivity. Furthermore, the experimentally observed discriminative fluorescence sensing property of TBNap-Ph and TBNap-Es towards VOAs was supported by computational calculations.

Structural and optical properties of composite phosphor Thx(MoO4)2/Bi2(1-x)Mo2O9; [formula omitted] doped with Ho3+/Yb3+ as a multifunctional materials

Composite phosphor’s, Thx(MoO4)2/Bi2(1-x)Mo2O9:2Ho3+/5Yb3+ have been synthesized cumulatively by facile co-precipitation process in ethylene glycol (EG) medium and subsequently placed for calcinations. Rietveld refinement of XRD patterns and FTIR analysis confirms the phase formation with a systematic variation of individual phases in dual-phase composite system [Th(MoO4)2-Orthorhombic; β-Bi2Mo2O9-Mononclinic]. Phase-dependent UV-Vis absorption of REs ions (Ho3+/Yb3+) has been observed and the difference between the optical bandgap of both phases leads to show the different aspect of the efficacy of optical properties. PL emission spectra of these phosphors show a strong green, relatively weak red and NIR emissions under λexci= 450 nm. The Yb3+ ions in the phosphor act as sensitizer and responsible for commencing the efficient UC emission, which shows nearly identical emission behavior under 980 nm excitation. Drastic changes in emission intensity (UC/DC) are observed with a relative dual-phase variation. Basically, the different crystal field scenarios around REs ions pertaining to both phases are responsible for the changes in emission intensity. The properties like dual-mode emission, phase dependent emission, color tuning properties, make them multifarious, that can be used for biological cell imaging, phototherapy, optical switching, display devices, solar cells, LEDs, etc.

Terpyridine-4-amino-1,8-naphthalimide chemosensor for discriminative fluorescent sensing of divalent metal cations at ppb level of sensitivity

A new terpyridine-4-amino-1,8-naphthalimide fluorescence sensor, TERPY-Nap, has been designed and synthesized in the analytically pure form via a one-step imidation reaction between 4-amino-1,8-naphthalic anhydride and N-[2,2′;6′,2″]Terpyridin-4′-yl-propane-1,3-diamine. The internal-charge-transfer (ICT) transition makes TERPY-Nap to be highly emissive and exhibits solvent polarity-dependent emission characteristics in different organic solvents. Inspired by the strong fluorescence, TERPY-Nap was used as an efficient fluorescence sensor for discriminative fluorescence sensing of divalent metal cations such as Cu(II), Co(II), and Ni(II) in ethanol. The initial fluorescence emission intensity of TERPY-Nap was quenched drastically upon the addition of Cu(II), Ni(II), and Co(II) ions as their nitrate salt, and the fluorescence quenching constants (KSV) were calculated to be in the order of 104–105 M−1. Furthermore, it was observed that TERPY-Nap can sense Cu(II), Ni(II), and Co(II) as low as ppb level of sensitivity and the quenched fluorescence emission of complexes can be reversed by the addition of well-known metal scavenger EDTA in ethanol. Interestingly, similar fluorescence titration studies using other metal ions like Zn(II), Cd(II), Mn(II), Ba(II), Al(III), Mg(II), and Ce(III) showed almost negligible changes in emission intensity due to their weak binding at the terpyridine receptor sites. Therefore, TERPY-Nap can be used as a potential ‘turn-off’ fluorescence chemosensor for reversible detection and trace analysis of biologically relevant and environmentally pertaining divalent metal cations.