Bathochromic Research Articles

A Facile and Efficient Synthesis of BODIPY-Based Fluorescent Probes for Selective Detection of Hydrazine.

A facile and ratiometric BODIPY-based fluorescent probe 4 was developed for the selective detection of hydrazine in solution phase. The BODIPY-based fluorophores 3 and 4 were easily prepared in high yields from the L-proline catalyzed reaction between α/β-formyl BODIPY 1 a/1 b and 3-cyanoacetylindole 2. Use of easily accessible substrates, benign solvent, catalytic amount of L-proline and high product yields are the advantageous features of the developed protocol. Prepared BODIPYs 3 (536 nm) and 4 (567 nm) showed bathochromic shifts (36-67 nm) in UV-Visible absorption maxima when compared to parent BODIPY (500 nm) in dichloromethane (DCM). The stable and economical BODIPY-based probe 4 exhibited rapid response and remarkable selectivity towards hydrazine when compared to other commonly occurring analytes. At low concentration, the BODIPY probe 4 (10 μΜ) is non-fluorescent, however, a significant enhancement in fluorescent (turn-on) was observed with the increasing concentration of hydrazine (0-100 μΜ). This change in fluorescent behaviour may be ascribed to intramolecular charge transfer (ICT) effect as supported by density functional theory (DFT) calculations. With a 4.3 μM detection limit, the BODIPY probe 4 was also found to be useful in detecting hydrazine in real environmental samples.

Triskelion-shaped Hexabenzocoronenes: Synthesis and Characterization of tris-substituted HBC derivatives.

The synthesis of unprecedented triskelion-shaped hexa-peri-hexabenzocoronenes with C3, C3h or D3h symmertry is reported. We present a new, five step synthetic access to tris-iodinated HBC derivatives carrying different solubilizing moieties (tert-butyl and mesityl), which serve as suitable building blocks for further functionalization. These molecules can undergo Sonogashira cross coupling reactions to obtain a series of seven ethynyl tris-substituted HBCs. The coupling partners range from carbon-based aromatic scaffolds (tBu-benzene, naphthalene, phenanthrene) to ligands for metal complexes (bipyridine, phenanthroline, terpyridine, acetylacetone). The optoelectronic properties were investigated by UV/vis absorption spectroscopy resulting in a significant batho-chromic shift of the absorption maximum compared to the iodinated starting material. Semiempirical calculations were used to determine the conformation and symmetry of the compounds.

Effect of co-pigments on anthocyanins of wild cranberry and investigation of interaction mechanisms

This study systematically evaluated the color-enhancing effects of different co-pigmented molecules (amino acids, peptides, flavonoids and phenolic acids) with cranberry anthocyanins under different environmental conditions (light, dark, high temperature and ascorbic acid) and their potential mechanisms by various means, such as degradation kinetics, color stability, H NMR spectroscopy, and structural simulation analyses. The results showed that the introduction of co-pigments induced a strong color-enhancing effect and bathochromic shift, inhibited the degradation of anthocyanins (9.34 % ~ 45.00 %), and prolonged the half-life of anthocyanins (14.33 % ~ 104.56 %). Among them, catechin, ferulic acid and tryptophan, by virtue of their large molecular planes, flexible side chains and abundant substituents, altered the core structure of anthocyanins and the electron cloud density of H atoms on the acylated molecules, which significantly enhanced their stability upon binding to anthocyanins. In addition, molecular docking simulations revealed an interaction mode between co-pigments and anthocyanins dominated by hydrogen bonding and π-π stacking interactions.

New Insights into pH-dependent Complex Formation between Lignosulfonates and Anthocyanins: Impact on Color and Oxidative Stability.

Anthocyanins have limited application as natural colorants and antioxidants due to their color loss and instability under certain conditions. This research explores the formation of a complex between lignosulfonates (LS) and cyanidin-3-O-glucoside (C3G) using a multitechnique approach as well as the effect on C3G's red color, oxidative stability, and antioxidant activity in acidic mediums. All data revealed pH-dependent LS-C3G interactions. The thermodynamic parameters showed weak noncovalent interactions, mainly electrostatic interactions, hydrogen bonds, and hydrophobic effect, with a higher association constant determined at pH 3. Fourier-transform infrared spectroscopy and Zeta-potential experiments further corroborate evidence of these LS-C3G interactions. Fluorescence quenching and lifetime experiments revealed static and dynamic quenching at pH 1 and 3, respectively. UV-visible spectroscopy demonstrated a bathochromic shift upon complex formation and a hyperchromic effect at pH 3 and 4, as a consequence of the improved red color of C3G. Electrochemical results suggested that at pH 3 the LS enhances C3G stability by protecting its oxidizable moieties over time, as well as improving the antioxidant activity of the anthocyanin in the complex.

Stimuli‐Responsive Optical Materials Based on Hypervalent Antimony‐Containing Conjugated Molecules

AbstractStimuli‐responsive materials have been applied for sensor devices because they can transform and amplify various target stimuli into observable signals. Much effort has been devoted to exploring effective molecular designs for obtaining stimuli‐responsive behaviors by taking advantage of the unique optoelectronic properties of π‐conjugated molecules involving various elements. This study focuses on the modulation of the electronic state of the π‐conjugated scaffolds by the oxidation number change of the hypervalent antimony. This study demonstrate that the strength of the intramolecular interaction between hypervalent antimony and the π‐conjugated framework can be tuned with ligand structure, substituent effect, and oxidation number shifts of hypervalent antimony. In particular, the color changes represented by hypsochromic and bathochromic wavelength shifts of optical bands are achieved by the oxidative reaction of hypervalent antimony in the solid state. Significantly, the direction of the color changes can be confidently predicted by quantum chemical calculations. The findings, based on the electronic interaction between π‐conjugated scaffolds and hypervalent main‐group elements, provide logical design strategies for advanced stimuli‐responsive materials.

N-Heterocycle-Substituted Hexa-peri-Hexabenzocoronenes with Windmill Architectures.

We describe the synthesis and computational investigation of N-heterocycle-substituted hexa-peri-hexabenzocoronenes (HBCs). Following our method for the preparation of thioether-substituted HBCs, we prepared pyrrole-, indole-, carbazole-, and 1H-benz[g]indole-substituted HBCs from the corresponding fluorinated precursors under microwave irradiation. A series of polysubstituted benzoindole-HBCs with windmill architectures was also synthesized using the polyfluorinated HBC analogs, and the substituent effects on the electronic properties of the HBC core were investigated. Similar to the thioether substituted HBCs, the nature of the heterocycle does not influence the optoelectronic properties of the HBC core. The attachment of multiple benzoindole substituents leads to a bathochromic shift of the absorption and emission spectra, comparable to our previous studies. Due to the circular arrangement of the benzoindole moiety, the attachment of multiple substituents results in the presence of multiple conformers at room temperature. The rotation barrier can be overcome by heating the compounds to 323-333 K. Additionally, the investigation of the relaxed geometries shows two π-stacking motifs within the conformers.

First oxidative coupling of cyclazine heterocycle via regioselective dimerization of 1,2-dicarbomethoxy-3-phenylcycl[3.2.2]azine: Synthesis, theoretical aspects and physicochemical studies

The first covalently linked dimer has been prepared for cyclazine systems by regioselective oxidative homocoupling of 1,2-dicarbomethoxy-3-phenylcycl[3.2.2]azine. The regioselectivity of this reaction at 4-position, having been confirmed by X-ray diffraction analysis and NMR spectroscopy, has been also reliably predicted within the model of average local ionization energy on the molecular surface of the starting monomer at the BP86/def2-TZVP level of theory. Due to the planar π-π interaction of the cycl[3.2.2]azine subunits, the dimer is a green fluorophore (λem = 527 nm, toluene), characterized by a bathochromic shift of the main bands in the UV–vis and fluorescence spectra relative to the monomer by 41 and 71 nm, respectively. Furthermore, the dimer demonstrates an increased fluorescence quantum yield relative to the monomer (55 % vs. 35 % in toluene), and according to the data of X-ray diffraction analysis, DFT calculations and variable temperature 1D and 2D 1H NMR spectroscopy, is characterized by hindered rotation of the S1-state-involved cycl[3.2.2]azine cores along the C4–C4′ bond axis. Such prerequisites determine good application potential of the 4-4′ coupled cycl[3.2.2]azine derivatives as turn-on fluorescent, i.e. fluorogenic probes for advanced bioimaging in living systems. Finally, unlike the monomer, the dimer shows reversibility of both one- and two-electron reduction and oxidation processes, and therefore can become the basis of both n- and p-type semiconductors.

Photovoltaic response promoted via intramolecular charge transfer in triphenylpyridine core with small acceptors: A DFT/TD-DFT study

Currently, A−π−A configured molecules (TTP1-TTP6) were designed from the reference compound (TPPR) by modifying the terminal acceptors for photovoltaic materials. Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) using the M06/6-311G(d,p) functional were employed to analyze the photonic and electronic properties of the newly designed derivatives. Various analyses; frontier molecular orbitals (FMOs), density of states (DOS), absorption spectra (λmax), transition density matrix (TDM), binding energy (Eb), hole-electron and open circuit voltage (Voc) were performed to explore the photovoltaic properties of triphenylpyridine based compounds. The structural modulation with acceptor moieties significantly tuned their HOMO and LUMO levels, resulting in reduced band gaps (2.833–3.037 eV). They also exhibited broader absorption spectra (λmax) ranging from 482.560 to 514.756 nm as compared to the reference compound (486.289 nm). Notably, TPP3 showed the good photovoltaic response as it displayed the least energy gap (2.833 eV) with lower binding energy (0.415 eV) and bathochromic shift (512.798 nm) in absorption spectra as compared to all other derivatives. Beside this, a comparative study with spiro-OMeTAD and P3HT standard hole transport materials illustrated that these materials can also be utilized as effective photovoltaic materials.

Effects of guar gum/chitosan edible films functionalized with citronellal/HPβCD inclusion complex on Harbin red sausage preservation

Harbin red sausage is a traditional local pork meat product in China, but it is susceptible to microbial contamination and lipid oxidation, leading to quality deterioration. Herein, guar gum (GG)/chitosan (CS) edible films functionalized with citronellal/hydroxypropyl-β-cyclodextrin inclusion complex (CIT/HPβCD-IC) were fabricated for Harbin red sausage preservation. Results demonstrated CIT/HPβCD-IC was successfully prepared and observed by SEM due to the bathochromic shift of maximum absorption peak of CIT, and the formation of new bonds was confirmed by FTIR analysis, suggesting the embedding of CIT into HPβCD cavity. The changes of functional groups stretching vibrations suggested successful loading of CIT/HPβCD-IC into the GG/CS edible films. Furthermore, the incorporation of CIT/HPβCD-IC enhanced the microstructural, mechanical and barrier properties, and improved the antibacterial activities, biodegradability and thermal stability of the GG/CS edible films. Particularly, the GG/CS edible films incorporated with 1 % CIT/HPβCD-IC (GG/CS-IC 1 %) enhanced the storage stability of Harbin red sausage at 4 °C by decreasing the weight loss rate, maintaining the pH, color, and textural stabilities, retarding the microbial growth and lipid oxidation of the sausage samples. Findings here suggested that GG/CS-IC 1 % edible films showed great potential as novel multi-functional edible packaging materials for Harbin red sausage preservation.

Tunable photoluminescence of electrosynthesized Ag2S@ZnSe quantum dots for nanomedicine applications

Quantum dots (QDs) synthesized from environmentally friendly precursors associated to scalable and high-efficiency production routes are essential for nanomedicine applications. Ag2S nanocrystal is notable by antimicrobial activity, photothermal properties, and low toxicity, making it promising bioactive nanomaterial. In this work, L-glutathione (GSH) capped Ag2S and ZnSe seeds were synthesized by using a fast and environmentally friendly electrochemical method (cavity cell, graphite powder macroelectrode and aqueous medium) and tested for biological applications. Ag2S nanocrystals presented a monoclinic structure (XRD analysis). The modulation of the optical properties was carried out by varying the Ag+/S2- ratio (1:1, 2:1, and 4:1), showing a photoluminescence hypsochromic shift from 916 to 759 nm, respectively. The modulation of the optical parameters was also carried out by the synthesis of Ag2S@ZnSe core/shell nanostructures. ZnSe seeds were prepared by the same electrochemical method and added to the Ag2S solution followed by thermal treatment under reflux (10 min). Ag2S@ZnSe systems showed higher photoluminescence intensity and a hypsochromic shift of the emission band using Ag2S cores (Ag+/S2- = 1:1 and 1:2), which was associated to the formation of alloy-type structures. In the case of the Ag2S@ZnSe (Ag+/S2- = 1:4), a bathochromic shift of the emission bands can be observed, which was associated to the formation of a core/shell structure. Ag2S@ZnSe QDs were tested in antimicrobial and cytotoxicity assays, showing a minimal inhibitory concentration (MIC) equal to 512 µg.mL−1. No cytotoxicity was observed against the Vero cell line at all concentrations tested (7.81–1000 µg.mL−1), and low cytotoxicity against the HT-29 tumor line (7.81–31.25 µg.mL−1), thus showing promising results for bioapplications.

Synthesis and spectroscopic characterization of 2-furancarbothioamide: N-(4-fluorophenyl)furan-2-carbothioamide

This investigation deals with an alternative thionation synthetic strategy for the preparation of N-(4-fluorophenyl)furan-2-carbothioamide using elemental sulphur and applying the Willgerodt-Kindler reaction. The carbothioamide was obtained with ca 30 % yield assessing the purity (higher than 90 %) with GC/MS spectrometry, and the compound was fully characterised by NMR (1H, 13C), FTIR and UV–visible spectroscopies. Indeed, 1H NMR spectroscopic analysis demonstrated that a single conformer with anti-anti geometry was formed attributed to the observation of only one N-H signal (9.37 ppm) of the NH-C=S group and, FTIR spectroscopy (N-H stretching at 3372 cm−1) also reinforces this observation. UV-visible absorption and fluorescence emission spectra were recorded in different polar and nonpolar solvents (acetonitrile, ethanol and n-heptane) and the λ0,0 cross point displays a bathochromic shift of 11 nm with the increasing solvent polarity. The fluorescence quantum yield (ϕf) has been measured at room temperature concluding that this carbothioamide derivative is not a fluorescent compound showing a ϕf value of 0.0002. Finally, theoretical calculations have been carried out to estimate the NMR chemical shifts as well as vibrational frequencies values of the anti-anti isomer and these values were compared with the experimental data obtaining satisfactorily correlations.

Copigmentation effect on red cabbage anthocyanins, investigation of their cellular viability and interaction mechanism

Anthocyanins (ANS) are an appealing substitute to synthetic colorants; but their practical applicability is limited due to low color stability. Copigmentation can improve both complex’s color stability as well as intensity. In this study, we examined the interaction of red cabbage ANS with copigments i.e., two organic acid, two phenolic acid, a flavonoid and three amino acid through experimental and theoretical approach. Among various copigments, phenolic and organic acids induced a strong bathochromic shift of 6.5–7.1 nm and 5.1–11.6 nm. Thermal analysis, anthocyanin content and chromaticity, were used to assess the color intensity and stability of ANS, at 4 ℃, 25 ± 2 ℃, sunlight, oxygen, and heat. Results revealed that oxalic acid copigmented complex followed by chlorogenic and rosmarinic acid exhibits significant thermal stability with greater retention rate at 120 ℃ and 150 ℃. In case of anthocyanin content and colorimetric parameters, chlorogenic acid followed by oxalic and rosmarinic acid exhibits significantly improved stability. Rosmarinic acid copigmented sample showed good cell viability at high concentration (200 µg/mL). Steered molecular dynamics and thermodynamic analysis reveals chlorogenic and rosmarinic acid as promising copigments involving conventional H-bonds, π-π interactions, and carbon hydrogen bonds.

Search for the smallest switch-on, water soluble and a phase-sensitive fluorimetric probe for lipid membranes: N-aryl isoindolin-1-one core

Studies of lipidous membranes are of utmost interest in biomedical applications, whereby fluorescent stains of membranes often play an essential role. Only a few stains are of small molecular weight, which could allow easier incorporation in lipid membranes. Here we present the discovery of a new structural entity applicable for membrane staining, 3-hydroxy-3-methyl-2-phenylisoindolin-1-one, whereby a study of a series of analogues (all Mw < 350) revealed their emission is strongly solvatochromic. Detailed studies revealed that fine-tuning of substituents strongly controls lipophilicity and emissive response, the optimum performance showing analogues with substituents on N-aryl moiety, particularly pronounced for p-hydroxy (5), o, p-dimethoxy (6) and p-methyl (7) derivatives, latter showing the highest logP. Chosen p-methyl (7) is characterised by the unique switch-on fluorescence in visible range upon membrane binding, based on very strong bathochromic shift (Δλ = +80–100 nm) between water (λ = 375 nm) and membrane (λ = 460 nm), in comparison to referent stain Laurdan® under the same conditions (Δλ = +20 nm). The novel neutral probe 7 prefers incorporation into the non-polar part of the lipid bilayers, not disturbing their properties. Future perspectives aim for the development of a structurally new group of low molecular weight lipid membrane stains, which eventually could be in situ tethered by “click” chemistry to the free propargyl bond of referent building block with a variety of additional functions.

Investigating Flavonoids by HPTLC Analysis Using Aluminium Chloride as Derivatization Reagent.

This is the first study to report on high performance thin layer chromatography (HPTLC) generated spectrophotometric data to systematically capture flavonoid compounds using optimized derivatization with either AlCl3 or NaNO2-AlCl3-NaOH as visualisation reagents. While the traditional AlCl3 colorimetric method using UV-Vis analysis provides valuable insights into the presence of flavonoids and allows derivation of the total flavonoid content (TFC) of a sample, HPTLC fingerprints obtained after spraying with AlCl3 or NaNO2-AlCl3-NaOH enable the visualization of the various flavonoids present in a sample based on their respective absorption shifts, thus complementing the traditional TFC assay. In this study, 40 different flavonoids representing different classes (flavonols, flavanolols, flavan-3-ol, flavones, flavanones, and isoflavonoids) were analysed. Upon derivatization with AlCl3 most of the investigated flavonoids recorded bathochromic shifts, yielding characteristic λmax values between 370 and 420 nm, while spraying with NaNO2-AlCl3-NaOH triggered hyperchromic shifts, and thus an increase in absorbance intensity in flavonoids with particular substitution patterns. A few non-flavonoid components with structural similarities to flavonoids (e.g., rosmarinic acid, gallic acid, aspirin, salicylic acid) served as the negative control in this study to determine whether the derivatization reagents allowed exclusive detection of flavonoids. The method was then applied to the analysis of flavonoid containing supplements as well as red clover honey to demonstrate the method's application in the analysis of natural products.

Fluorescence Modulation through the Inverted Energy Gap Law in Triply N─B←N‐Containing Windmill‐Shaped Triazines

A series of windmill‐shape heterocyclic molecules containing three N─B←N units, TBN and its derivatives, with quasi‐planar C3 symmetric backbone, are synthesized. The parent TBN exhibits a strongly allowed, doubly degenerate lowest excited state but suffers from very low fluorescence, due to very fast nonradiative decay rate through a conical intersection (CI) as revealed by femtosecond transient absorption spectroscopy and quantum‐chemical calculations. Introducing peripheral phenyl‐ or thienyl‐groups (Ph‐TBN or Th‐TBN) induces pronounced bathochromic shifts and enhances fluorescence, which is beneficial from inhibited nonradiative pathway by the increased energy barriers to access the CI at excited state. The understanding of this rather uncommon behaviour may open routes for the design of novel fluorescence materials.

Fluorescence Modulation through the Inverted Energy Gap Law in Triply N─B←N-Containing Windmill-Shaped Triazines.

A series of windmill-shape heterocyclic molecules containing three N─B←N units, TBN and its derivatives, with quasi-planar C3 symmetric backbone, are synthesized. The parent TBN exhibits a strongly allowed, doubly degenerate lowest excited state but suffers from very low fluorescence, due to very fast nonradiative decay rate through a conical intersection (CI) as revealed by femtosecond transient absorption spectroscopy and quantum-chemical calculations. Introducing peripheral phenyl- or thienyl-groups (Ph-TBN or Th-TBN) induces pronounced bathochromic shifts and enhances fluorescence, which is beneficial from inhibited nonradiative pathway by the increased energy barriers to access the CI at excited state. The understanding of this rather uncommon behaviour may open routes for the design of novel fluorescence materials.

Positional isomers and non-covalent interactions of acrylonitrile-methylpyridinium iodide salts: Combined experimental and quantum chemical calculations investigations

Quaternary salts d-π-A+X- having a large π-conjugated system (I) 2-((Z)-1-cyano-2-[4-(dimethylaminophenyl]ethenyl)-1-methylpyridin-1-ium iodide, (II) 3-((Z)-1-cyano-2-[4-(dimethylaminophenyl]ethenyl)-1-methylpyridin-1-ium iodide, and (III) 4-((Z)-1-cyano-2 iodide -[4-(dimethylaminophenyl]ethenyl)-1-methylpyridin-1-ium iodide, were synthesized straightforwardly and easily and characterized by single-crystal X-ray diffraction, IR, UV–Vis, 1HNMR spectroscopy, DSC, and TGA. Quantum chemical calculations were performed to obtain electronic structure by using DFT. The salts I-III exhibited a hyperchromic shift and a strong bathochromic effect of 100 nm compared to the precursors, which indicates charge transfer (CT) due to ionic interactions. The Hirshfeld, MEPS, QTAIM, and NCI-RDG analyses showed that the -CN group and the counterion I(-) atom play major roles in the intermolecular interaction for crystal packing. The significance of non-covalent interactions for the stability of the molecules in their solid state is also revealed by natural bond orbital analysis.

Conformation‐Confined Organic Butterfly‐Molecule with High Photoluminescence Efficiency, Deep‐Blue Amplified Spontaneous Emission, and Unique Piezochromic Luminescence

AbstractOrganic fluorophores with tunable π‐conjugated paths have attracted considerable attention owing to their diverse properties and promising applications. Herein, we present a tailored butterfly‐like molecule, 2,2’‐(2,5‐bis (2,2‐diphenylvinyl)‐1,4‐phenylene)dinaphthalene (BDVPN), which exhibits diverse photophysical features in its two polymorphs. The BP phase crystal, with its “aligned wings” conformation, possesses emissive characteristics that are nearly identical to those in dilute solutions. In contrast, the BN phase crystal, which adopts an “orthogonal wings” conformation, exhibits an unusual hypsochromic‐shifted emission compared to its dilute solution counterparts. This intriguing hypsochromic‐shifted emission originates from the reduction in the effective conjugated length of the molecular skeleton. Notably, BN phase crystals also exhibit exceptional optical performance, featuring high‐efficiency emission (76.6 %), low‐loss optical waveguides (0.571 dB mm−1), deep‐blue amplified spontaneous emission (ASE) with narrow full width at half maximum (FWHM: 6.4 nm), and a unique 200 nm bathochromic shift of piezochromic luminescence.

Conformation-Confined Organic Butterfly-Molecule with High Photoluminescence Efficiency, Deep-Blue Amplified Spontaneous Emission, and Unique Piezochromic Luminescence.

Organic fluorophores with tunable π-conjugated paths have attracted considerable attention owing to their diverse properties and promising applications. Herein, we present a tailored butterfly-like molecule, 2,2'-(2,5-bis (2,2-diphenylvinyl)-1,4-phenylene)dinaphthalene (BDVPN), which exhibits diverse photophysical features in its two polymorphs. The BP phase crystal, with its "aligned wings" conformation, possesses emissive characteristics that are nearly identical to those in dilute solutions. In contrast, the BN phase crystal, which adopts an "orthogonal wings" conformation, exhibits an unusual hypsochromic-shifted emission compared to its dilute solution counterparts. This intriguing hypsochromic-shifted emission originates from the reduction in the effective conjugated length of the molecular skeleton. Notably, BN phase crystals also exhibit exceptional optical performance, featuring high-efficiency emission (76.6 %), low-loss optical waveguides (0.571 dB mm-1), deep-blue amplified spontaneous emission (ASE) with narrow full width at half maximum (FWHM: 6.4 nm), and a unique 200 nm bathochromic shift of piezochromic luminescence.

Organohalogenochromism: Toward Colorimetric Detection of Volatile Organic Halogen Compounds

A significant hypsochromic or bathochromic shift of photoabsorption bands of dyes may be observed only in halogenated solvents. Such specific solvatochromism is termed organohalogenochromism (OHC), which has been recently recognized as a photophysical phenomenon. However, few studies have been carried out on the elucidation of OHC and thus there is a limited insight into the mechanism for expression of OHC, although the phenomenon not only is of a great scientific interest in photochemistry, photophysics, analytical chemistry, and synthetic organic chemistry but also has great potential for development of colorimetric detection technique for organohalogen compounds; this technique is expected to be facile operation and simple analysis with sufficient accuracy, high sensitivity, and fast response, and thus allows visualization and real‐time monitoring for toxic volatile organohalogen compounds (VOHCs). In this Concept, we first review OHC of dyes which have been reported so far. Second, the elucidation of OHC based on the interactions between dye and organohalogen molecules are discussed. In particular, we propose the explanation for a pronounced OHC of donor‐π‐acceptor‐type cationic dye from the viewpoint of halogen bond (XB) between halogenated solvents and counter anion of cationic dye. Moreover, an application of organohalogenochromic dyes to colorimetric sensors for VOHCs is presented.