Cyan Fluorescence Research Articles

Multicolor emissive hyperbranched polysiloxanes from enhanced spatial electronic communication for security encryption and bacteria imaging

Unconventional fluorescent polymers with long-wavelength emission have attracted considerable attention due to their facile preparation, good biocompatibility, and excellent processability. However, their emission at long-wavelength is relative low. Herein, a series of aromatic amino acids functionalized hyperbranched polysiloxanes with deep red to cyan fluorescence were prepared. Experimental and theoretical calculation results show that the long-wavelength emission comes from the spatial electronic delocalization among conjugated π bonds and electron-rich functional groups. The balance between rigidity and flexibility is favorable for the strong long-wavelength emission. Moreover, the polymers’ fluorescence is sensitive to Fe3+ and OH– ions; and these polymers show potential applications in security encryption, fluorescent stamp inks and bacteria multicolor fluorescence imaging. This work provides an efficient method for the development of long-wavelength emissive unconventional fluorescence polymers

Bright and Stable Cyan Fluorescent RNA Enables Multicolor RNA Imaging in Live Escherichia coli.

Fluorescent RNAs (FRs), which are RNA aptamers that bind and activate their cognate small fluorogenic dyes, have provided a particularly useful approach for imaging RNAs in live cells. Although the color palette of FRs is greatly expanded, a bright and stable cyan FR with good biocompatibility and biorthogonality with currently available FRs remains desirable but is not yet developed. Herein, the development of Myosotis is described, an RNA aptamer that emits bright cyan fluorescence upon binding a novel GFP chromophore-like fluorophore called DBT. Myosotis has a nanomolar affinity for DBT and shows a weak dependence on magnesium for folding. Further studies reveal that the Myosotis-DBT complex has a long fluorescence lifetime, good photostability, and enhance cellular brightness. It is further shown that Myosotis-DBT is biorthogonal to Pepper and Clivia FRs, allowing multiplex fluorescence imaging of RNA in live bacteria. Myosotis can also use to image mRNA in live bacteria, revealing potential coupling between mRNA translation and stability. It is believed that this cyan FR will be a useful tool for studying the functionality and mechanism of RNA underlying diverse biological processes.

A ratiometric fluorescent probe based on phenothiazine and quinazolinone for rapid detection of ClO− and its application

A novel fluorescent probe (BPQ-1) with large conjugated system (phenothiazine was conjugated with quinazolinone) was synthesized. BPQ-1 showed a remarkable ratiometric fluorescence response to ClO− within 10 s, and achieved large stokes shift (168 nm), high sensitivity (LOD = 16.7 nM) and excellent selectivity. Among the analytes to be detected, there is a significant change from bright yellow fluorescence to cyan fluorescence only when ClO− is added to BPQ-1. Through density functional theory calculation and mass spectrometry experiments, the fluorescence response mechanisms of the BPQ-1 are given. In addition, BPQ-1 has been successfully applied to the detection of ClO− in real water samples and test strips for detecting ClO− with different concentrations have been prepared. In particular, the probe has been successfully applied to the fluorescence imaging of exogenous ClO− in living cells.

Reversible Structural Phase Transitions in Zero-Dimensional Cu(I)-Based Metal Halides for Dynamically Tunable Emissions.

Exploring structural phase transitions and luminescence mechanisms in zero-dimensional (0D) metal halides poses significant challenges, that are crucial for unlocking the full potential of tunable optical properties and diversifying their functional capabilities. Herein, we have designed two inter-transformable 0D Cu(I)-based metal halides, namely (C19H18P)2CuI3 and (C19H18P)2Cu4I6, through distinct synthesis conditions utilizing identical reactants. Their optical properties and luminescence mechanisms were systematically elucidated by experiments combined with density functional theory calculations. The bright cyan-fluorescent (C19H18P)2CuI3 with high photoluminescence quantum yield (PLQY) of 77 % is attributed to the self-trapped exciton emission. Differently, the broad yellow-orange fluorescence of (C19H18P)2Cu4I6 displays a remarkable PLQY of 83 %. Its luminescence mechanism is mainly attributed to the combined effects of metal/halide-to-ligand charge transfer and cluster-centered charge transfer, which effects stem from the strong Cu-Cu bonding interactions in the (Cu4I6)2- clusters. Moreover, (C19H18P)2CuI3 and (C19H18P)2Cu4I6 exhibit reversible structural phase transitions. The elucidation of the phase transitions mechanism has paved the way for an unforgeable anti-counterfeiting system. This system dynamically shifts between cyan and yellow-orange fluorescence, triggered by the phase transitions, bolstering security and authenticity. This work enriches the luminescence theory of 0D metal halides, offering novel strategies for optical property modulation and fostering optical applications.

Polyvinyl alcohol fiber with enhanced strength and modulus and intense cyan fluorescence based on covalently functionalized graphene quantum dots

Polyvinyl alcohol fiber with enhanced strength and modulus and intense cyan fluorescence based on covalently functionalized graphene quantum dots

A ratiometric, turn-on fluorosensor for specific detection of Zn2+ ions

A potentially active fluorescent chemosensor (E)-2-(((2-(1H-benzo[d]imidazol-2-yl)phenyl)imino)methyl)-5-(diethylamino)phenol (BMDP) is developed by the condensation of 2-(2-aminophenyl)-1H-benzimidazole and 4-(diethylamino)salicylaldehyde. It shows an exceptional ratiometric fluorescence behavior when exposed to Zn2+ ions and the photoluminescence color is changed from blue to cyan under the exposure of a 365 nm UV light which is also strongly evident from the color chromaticity diagram. The exceptional ratiometric fluorescence behavior in the presence of Zn2+ ions is found to be due to the chelation-enhanced fluorescence (CHEF). The 1:1 stoichiometry of BMDP and Zn2+ ions in Zn2+ ions chelated BMDP complex is confirmed through Job’s plot analysis. Remarkably, Cd2+ does not interfere with the selective ratiometric fluorescence behavior induced by Zn2+ ions. The lowest detection limit and quantification limit are estimated to be 28 nM and 92 nM respectively. The cyan fluorescence of the Zn2+ ions chelated BMDP complex is interestingly reversed to the original BMDP in the presence of ethylenediamine tetraacetic acid (EDTA). At the molecular level, this can be thought of as a complimentary “INHIBIT” logic gate. Furthermore, it is possible to utilize the probe for on-site identification in test strips with improved Zn2+ ions selectivity. We have also used a smartphone-based method to demonstrate the usefulness of BMDP for the immediate quantification and detection of Zn2+ ions. In light of this, probe BMDP is a trustworthy fluorescence probe for on-site monitoring that can accurately identify Zn2+ ions even when some other metals and anions compete.

Determination of the Course of Cyan Fluorescence of Pseudomonas aeruginosa with a Handheld Bacterial Imaging Device.

Chronic wound infections are of clinical concern as they often lead to high rates of mortality and morbidity. A point-of-care handheld bacterial fluorescence imaging has been designed to detect the auto-fluorescent characteristics of most clinically relevant species of bacteria. This device causes most species of bacteria to exhibit red fluorescence due to the production of exoproduct porphyrins. One of the most significant contributors to the pathogenicity of chronic wounds is the pathogen Pseudomonas aeruginosa, and interestingly, this organism exhibits an additional unique cyan fluorescence signature. There is an over 90% positive predictive value that, when a chronic wound exhibits cyan fluorescence with the bacterial fluorescence imaging device, the wound will harbor P. aeruginosa. This project seeks to understand what genetic factor(s) contribute to the cyan phenotype observed.

Water-soluble polymeric probe with tryptophan pendants for formaldehyde sensing

Formaldehyde (FA) is a grade-I carcinogen and the most reactive aldehyde in the carbonyl family, posing substantial health hazards. Herein, a water-soluble polymeric probe with side-chain tryptophan pendants is proposed that relies on an FA-induced Pictet-Spengler reaction for FA sensing in an aqueous medium. The polymeric probe shows cyan fluorescence in an aqueous medium after the interaction with FA due to the formation of a β-carboline derivative, confirmed by high-resolution mass spectrum analysis of the product from the model reaction between tryptophan methyl ester and FA. The copolymer’s sensitivity to FA in aqueous solutions at the nanomolar level is estimated using the fluorescence titration method, where ∼20-fold enhancement in fluorescence intensity is observed within 2 min when 200 µM FA is added to the aqueous solution of the copolymer. The probe can selectively detect FA using colorimetric and fluorometric methods with a detection limit as low as 25 nM. The FA-sensing mechanism is studied from the model reaction of tryptophan methyl ester (TME) with FA, and density functional theory (DFT).

Terminal halogen-containing rod-like liquid crystals: Synthesis, self-assembly, photophysical and mechanochromism properties

Five series of cyanostilbene-based rod-like liquid crystals containing one different terminal atom (H, F, Cl, Br and I) at one end and one terminal aliphatic chain with different numbers of carbon atoms at the other end were reported by Suzuki coupling and Knoevenagel reactions. The influence of terminal halogen atoms and terminal chain length on the self-assembly, AIE behavior, temperature-dependent emission and mechanochromism behavior was explored by POM, DSC, XRD, SEM, absorption spectra and emission spectra. All the compounds are enantiotropic liquid crystals. The lowest non-halogen substituted homologue exhibited solo N phase, but the higher non-halogen substituted homologues exhibited mesogenic transition from SmA phase to N phase upon rising temperature. All the lowest halogen substituted homologues exhibited mesogenic transition from SmA phase to N phase upon rising temperature and all the higher homologues only exhibited SmA. The distinct mesogenic phase transition could be attributed to the intermolecular interaction produced by terminal halogen and the rigidity of the terminal aliphatic chain. All the non-halogen substituted compounds and halogen substituted compounds with smaller terminal halogen atom (F, Cl and Br atom) exhibited AIE behaviors, whereas the iodinated compounds exhibited extremely weak emission in solution and aggregated states due to the heavy atoms effect. These compounds also exhibited distinct solid-state emission with blue or cyan fluorescence, which could be quenched by increasing temperature. The reversible mechanochromism behavior was also achieved in all the compounds. The mechanical force induced quench in emission in non-halogen substituted compounds and halogen substituted compounds with smaller terminal halogen atom (F, Cl and Br atom), whereas enhancement in iodinated compounds. The reversible mechanochromism behavior endowed these compounds with potential applications in rewritable paper and anti-counterfeiting. The interesting properties in these liquid crystals would be attributed to the balance of the halogen-halogen interactions, heavy atom effect, steric-hindrance effect and chain length. These investigations would be helpful to understand the relationship between chemical structures and properties.

Fluorometric and naked eye detection of cadmium ion by reduced Schiff base zinc-based probe in potable water: Theoretical and experimental approach

Alarmingly increasing population and industrial growth has immensely affected water bodies and potable water sources by elution of many heavy toxic metal ions, including cadmium (II). The rising threat has demanded easy and cost-effective detection of this heavy metal ion so as to spread widely across the masses and eliminate the poisoning of water. With this aim, we have synthesized a zinc-based fluorescent probe (rBDZn) having reduced Schiff base backbone with N- and O- donor atoms derived from 5-bromosalicaldehyde and 2,2-dimethylpropane-1,3-diamine, characterized with the aid of single crystal X-ray analysis, revealing a trimeric structure linearly bridged by azide ion. The complex has been found to exhibit a cyan blue fluorescence getting ‘turned-off’ in the presence of cadmium ion selectively along with many other cations in the aqueous solution together with a naked-eye visible color change from pale yellow to colorless. Steady-state and time-resolved fluorescence titration, and absorption titration experiments were performed. During the investigation of the sensing pathway it is observed that the detection of Cd2+ is being associated with the formation of the cadmium complex rBDCd from the probe rBDZn and this has been explained though a probable mechanism. In support of the fact a single crystal of Cd-substituted complex have been isolated and verified with single crystal XRD and computational calculations. Proper justification of the selectivity of the probe towards cadmium ion with a very low detection limit of 1.72 nM enables its genuine impact in the pollution management.

Color-reversible fluorescence tracking for the dynamic interaction of SO2 with Hg2+ in living cells

Mercury ion (Hg2+) is one of the most threatening substances to human health, and the mercury poisoning can damage physiological homeostasis severely in human, even cause death. Intriguingly, Sulfur dioxide (SO2), a gas signal molecule in human, can specifically interact with Hg2+ for relieving mercury poisoning. However, the dynamic interaction of Hg2+ with SO2 at the tempospatial level and the correlation between Hg2+ and SO2 in the pathological process of mercury poisoning are still elusive. Herein, we rationally designed a reversible and dual color fluorescent probe (CCS) for dynamically visualizing Hg2+ and SO2 and deciphering their interrelationship in mercury poisoning. CCS held good sensitivity, selectivity and reversibility to Hg2+ and SO2, that enabled CCS to specifically detect SO2 and Hg2+ via cyan fluorescence channel (centered around 485 nm) and red fluorescence channel (centered around 679 nm), respectively. Notably, the separate fluorescence signal changes of CCS realized the dynamic tracing of Hg2+ and SO2 in living cells, and presented the potential for exploring the correlation between SO2 and Hg2+ in mercury poisoning.

Multidimension‐Regulated Dynamic Timing Control Over Multicolor Emission of Host–Guest Assemblies for Information Encryption and Advanced Anti‐Counterfeiting

AbstractDynamical control over molecular luminescence, especially in a time‐dependent manner, holds great promise for the development of smart luminescent materials for anti‐counterfeiting and preventing information leakage. Herein, a series of self‐assembled systems are reported using pillar[5]arene (DMP[5]) and spiropyran derivatives (SP‐C4‐Py). The assemblies rely on the time‐encoded locking and unlocking ring‐switching and fluorescence resonance energy transfer (FRET) units for information camouflage and multilevel encryption. DMP[5] with cyan solid fluorescence color acts as the host and energy transfer (EnT) donor, while photochromic SP‐C4‐Py with the ring‐opened and closed isomers acts as guest and EnT acceptor. When irradiated, the assemblies undergo a time‐dependent luminescence color change ranging from cyan to yellow to red through a FRET process. The molar ratio of host and guest in the assembly systems affects the FRET efficiency, and the power of the irradiation source influences the isomerization degree and rate of SP‐C4‐Py, allowing for precise control over the fluorescent color transition time. The combination of molecular composition and external stimuli governs the kinetics of color change, resulting in a difference in the appearance time of a specific fluorescent color pre‐designed as correct authorized information. By combining these diverse assembles in one label, information encryption and dynamic information identification are achieved in the dimensions of time, ratio, and light power. This time‐dependent feature offers the assembly materials with a multilevel security and provides new possibilities for anti‐counterfeiting and blocking information leakage.

Synthesis, characterization, hysteretic two-step CO2 adsorption, and fluorescence properties of two isoreticular mixed-ligand pillared-layer frameworks

Two isostructural and isomorphrous metal–organic frameworks (MOFs), namely [Zn2(Brtpt)2 (bpBTD)]n (1) and {[Zn2 (ntpt)2 (bpBTD)]∙solvent}n (2), where bpBTD = bis(pyridin-4-yl)benzothiadiazole, H2Brtpt = 2-bromoterephthalic acid, H2ntpt = 2-nitroterephthalic acid, with thermal stability of 355 °C for 1 and 265 °C for 2 were hydro (solvo)thermally synthesized in DMF/H2O media at 100 °C. Single-crystal X-ray diffraction analysis revealed that 1 and 2 both possess 2-fold interpenetrating pillared-layer frameworks showing pcu net topology with the point symbol of 41,263. The sufficient extra-framework void spaces are approximately 30.1 % for 1 and 32.0 % for 2 with open channels along the b axis, where the window sizes are ca. 5.51 × 3.15 Å2 in edge for the former and ca. 5.47 × 3.44 Å2 and 3.12 × 3.44 Å2 in edge for the latter. Gas adsorption isotherms revealed that thermally activated 1 and 2 both hardly adsorb N2 with very low N2 uptakes at 77 K. Comparably, the CO2 adsorption isotherms of thermally activated 1 and 2 both revealed gate-opening (two-step) sorption behaviors with an apparent hysteretic adsorption–desorption process, where the maximum uptakes are 135.4 and 171.5 cm3 g−1 STP for 1 and 2, respectively, at 195 K and P/P0 = 1. Photoluminescence studies showed that 1 and 2 both emitted bpBTD-dominated ligand-centered emissions, being as cyan and pearl aqua color fluorescence centered at λem = 467 and 495 nm, respectively, in solid-state and as cyan color fluorescence centered at λem = 455 and 458 nm, respectively, in H2O suspensions.

Mechanically Ultra-Robust Fluorescent Elastomer for Elaborating Auxetic Composite.

Fluorescent elastomers are predominantly fabricated through doping fluorescent components or conjugating chromophores into polymer networks, which often involves detrimental effects on mechanical performance and also makes large-scale production difficult. Inspired by the heteroatom-rich microphase separation structures assisted by intensive hydrogen bonds in natural organisms, an ultra-robust fluorescent polyurethane elastomer is reported, which features a remarkable fracture strength of 87.2MPa with an elongation of 1797%, exceptional toughness of 678.4MJm-3 and intrinsic cyan fluorescence at 445nm. Moreover, the reversible fluorescence variation with temperature could in situ reveal the microphase separation of the elastomer in real time. By taking advantage of mechanical properties, intrinsic fluorescence and hydrogen bonds-promoted interfacial bonding ability, this fluorescent elastomer can be utilized as an auxetic skeleton for the elaboration of an integrated auxetic composite. Compared with the auxetic skeleton alone, the integrated composite shows an improved mechanical performance while maintaining auxetic deformation in a large strain below 185%, and its auxetic process can be visually detected under ultraviolet light by the fluorescence of the auxetic skeleton. The concept of introducing hydrogen-bonded heteroatom-rich microphase separation structures into polymer networks in this work provides a promising approach to developing fluorescent elastomers with exceptional mechanical properties.

Nitrogen-doped carbon dots for 3D printed smartphone-assisted cascade visual detection of morin and aluminium ion, solid fluorescence ink

With the growing emphasis on health management, individuals increasingly focus on monitoring drug molecular residues and harmful ions. Motivated by the concepts of the intelligent system and quantitative detection, we develop a smartphone-assisted cascade visual sensing device based on nitrogen-doped carbon dots (N-CDs) for in-site quantitative detection of morin and aluminium ion (Al3+). Initially, citric acid and o-phenylenediamine are identified as precursors for N-CDs synthesis via the microwave-assisted hydrothermal treatment. Subsequently, systematic studies reveal that the fluorescence of N-CDs is quenched upon the introduction of morin because of the inner filter effect (IFE). Conversely, the fluorescence recovery phenomenon occurs after the cascade addition of Al3+ since the morin binds with Al3+, resulting in the inhibition of IFE. Simultaneously, the fluorescence recovery of N-CDs enhances the cyan fluorescence emission of morin/Al3+. Based on the fluorescence quenching and recovery behavior, morin and Al3+ can be detected in the ranges of 0.070–50 μM and 0.124–40 μM with low detection limits of 0.070 μM and 0.124 μM, respectively. Furtherly, a smartphone-assisted cascade visual sensing device is designed for in-site quantitative detection of morin and Al3+. Moreover, based on the strong fluorescence and concentration-dependent emission behavior of N-CDs, the multi-color fluorescent ink is developed successfully. This work not only offers an excellent solution for simultaneous detection of morin and Al3+ but also shows numerous opportunities for solid lighting, information encryption and flexible optics.

Polyethyleneimine-derived fluorescent conjugate for trace-level detection of multiple ions via signal amplification

Fluorescent conjugates, based on polyethyleneimine were prepared by incorporating salicylaldehyde and 2-hydroxynaphthaldehdye respectively in the aqueous medium. The polymer derived from salicylaldehyde showed a dual-mode response with Cu2+ and Zn2+ ions. The addition of Zn2+ could change the cyan fluorescence into a blue-colored one, while the Cu2+ ion could result in a turn-off response. On the contrary, the polymer functionalized with 2-hydroxynaphthaldehdye showed fluorescence response only with Cu2+ ions. The fluorescent polymers prepared at different polyethyleneimine and salicylaldehyde ratios not only showed the formation of nanoparticles of different sizes but also, interacted with Cu2+ ions to different extents. The mechanistic investigation suggested that the enhanced sensitivity of such fluorescent nanoparticles was due to the signal amplification attributed to the polymeric backbone. Further, the in-situ synthesized Cu and Zn complex of polymers showed interaction with pyrophosphate in the aqueous medium. However, the mode of interaction as well as fluorescence response depended on the nature of the metal ions involved.

An Adenine‐Based Chromone‐Coupled ‘Off‐On‐Off’ Fluorogenic Dyad for Cascade Detection of Zn2+ and HSO₄− Ions or Zn2+ Ions and Picric Acid

AbstractA chromone‐coupled adenine‐based fluorogenic chemosensor (BD1) has been introduced for cascade detection of Zn2+ and HSO4−ions or Zn2+ and picric acid (PA) based on the fluorescence ‘OFF‐ON‐OFF’ mechanism. A momentous fluorescence improvement has been observed due to the accumulation of Zn2+ ions in the BD1 solution because of the formation of the Zn2+ chelated BD1 complex. A cyan color fluorescence enhancement is visible under the exposure of a 365 nm UV lamp, which is also manifested in the CIE diagram. The detection limit of our developed sensor BD1 and Zn2+−BD1 complex towards the identification of Zn2+ and HSO4− ions are in the nM and μM range, respectively, in the solution phase. Among the several explosive nitroaromatic compounds (NACs), only PA quenches the fluorescence of the Zn2+ chelated BD1 complex, and the nature of quenching is both static and dynamic. A paper strips‐based test kit experiment is performed for on‐spot identification of Zn2+ ions and PA. Based on these chemically encoded inputs and the fluorescence intensity as optical output, we have constructed an INHIBIT molecular logic circuit. The present report evokes a new approach for the development of new chemosensors from bioinspired materials such as adenine, a purine nucleobase.

Specific detection of sarin gas Mimicking, diethylchlorophosphate employing solvent mediated in-situ generated hydroxyl functional group in a phthalimide-chromone coupled fluorogenic probe

Nerve agents are particularly hazardous substances and can result in fatality due to suppressing acetylcholinesterase function. This article introduced a fluorescent probe, (E)-5-(((4-hydroxy-2-methoxy-2H-chromen-3-yl)methylene)amino)isoindoline-1,3-dione (CMAD), which was exceptionally effective at detecting the sarin replacement diethylchlorophosphate (DCP), both in solution and vapor phase, respectively which exhibited quick response, excellent sensitivity and specificity. As a result of the gradual addition of DCP into the solution of the probe, the photoluminescence intensity at 476 nm is markedly increased, exhibiting bright cyan color fluorescence because of inhibition of the excited state intramolecular proton transfer (ESIPT) process, which is also clearly reflected in the estimation of photoluminescence quantum yield of phosphorylated CMAD (0.55 relatives to 4-aminophalimide) and the color chromaticity (CIE) diagram. The lowest detection limit and limit of quantification are 3.25 µM and 10.8 µM, respectively, within the stockpiles of other analogous analytes. Additionally, for on-the-spot detection, the probe may also be utilized in the test strips with superior selectivity for DCP. The ability to identify and measure DCP in the gas phase has also been established using a dip-stick and dipped-vial-conical-flask analysis. Moreover, we also performed the smartphone-based technique for the practical utility of CMAD for the on-spot quantification and detection of sarin gas in real threat situations. The effective demonstrations of practical usage, including soil analysis, inspire additional applications in different fields. Therefore, probe CMAD is a reliable, on-site monitoring fluorescence probe for precisely identifying DCP in the presence of additional competing nerve agents.

Multiple Force-Triggered Downconverted and Upconverted Emission in Polymers Containing Diels-Alder Adducts.

Fluorescent mechanophores can indicate the deformation or damage in polymers. The development of mechanophores with multi-triggered response is of great interest. Herein, Diels-Alder (DA) adducts are incorporated into linear poly(methyl acrylate) PMA-BA and network poly(hexyl methacrylate) (PHMA) as mechanophores to detect the stress caused by ultrasound, freezing, and compression. The DA mechanophores undergo retro-DA reaction to release 9-styrylanthracene chromophore upon applying force, resulting in cyan fluorescence. The dissociation ratio of the DA mechanophore after pulsed ultrasonication of PMA-BA solution for 240 minutes is estimated to be 52 % by absorption spectra and 1H NMR. Additionally, the rate constant of mechanical cleavage is calculated to be 1.2×10-4 min-1⋅kDa-1 with the decrease in molecular weight from 69 to 22 kDa measured by gel permeation chromatography. Freezing of PHMA gels as well as compression of PHMA bulk samples turn-on the DA mechanophores, revealing the microscale fracture. Photon upconversion responses toward various force stimuli are also achieved in both polymer solutions and bulk samples by doping platinum octaethylporphyrin (PtOEP) or palladium meso-tetraphenyltetrabenzoporphyrin (PdTPTBP) sensitizers with multiple excitation wavelengths.

Role of Halobenzene Guest Molecules in Modulating Room Temperature Phosphorescence of Benzophenone-Naphthalene Diimide Inclusion Crystals.

Materials exhibiting room temperature phosphorescence (RTP) have recently emerged as a subject of significant interest. In this study, we successfully created inclusion crystals by introducing halobenzenes as guests into a host molecule combining benzophenone with naphthalene diimide. This approach led to the creation of fascinating fluorescence and RTP properties dependent on the guest molecules. Notably, crystals containing chlorobenzene showed cyan fluorescence, while those with iodobenzene displayed red RTP. This difference highlights the impact of the guest molecule on the luminescent properties, with the significant external heavy-atom effect of iodobenzene playing a key role in promoting efficient intersystem crossing between the excited singlet and triplet states. Crystals with bromobenzene exhibited a unique blend of fluorescence and RTP, both from benzophenone and naphthalene diimide, highlighting the moderate heavy-atom effect. These findings reveal composite materials with remarkably diverse and interesting optical characteristics.