Photoinduced Intramolecular Charge Transfer Research Articles

Electrochemical synthesis of donor-acceptor triazine based polymers with halochromic and electrochromic properties

Two triazine monomers substituted with aromatic α,β unsaturated ketones (chalcones) as connecting arms, holding triphenylamine or carbazole ending groups, were by the first time synthesized using commercial and inexpensive starting materials in just two steps. Triphenylamine and carbazole groups were strategically introduced in order to allow electrochemical polymerization and redox activity of the obtained films. The chalcone, together with the triphenylamine or carbazole outer groups, give rise to the formation of a donor-acceptor systems, allowing the generation of photoinduced intramolecular charge transfer (ICT) electronic transitions and providing basic sites for protonation. Because of the star-like chemical structure of the used triazine, electrochemical polymerization of these monomers conducted to the formation of hyperbranched structures. The polymeric materials exhibited not only electrochromic properties but also showed a halochromic behavior. Spectroelectrochemical studies of the films showed different colorations in the three redox states (neutral, semioxidized and fully oxidized). The color changes are fast and easily detected by the naked eye. Electrochemical parameters such as optical contrast, coloration efficiency, optical memory, and long-term stability for both films were obtained and compared. A quasi-solid window-type electrochromic device was assembled using the electrogenerated polymer with the best electrochromic performance and stability. Moreover, the triphenylamine based polymer showed reversible color changes upon acid-base vapor exposure cycles, demonstrating that this polymer can be used not only in electrochromic devices but also in acid vapor sensors.

Ethyl 3-aminobenzo[b]thiophene-2-carboxylate Derived Ratiometric Schiff Base Fluorescent Sensor for the Recognition of In3+ and Pb2.

An ethyl 3-aminobenzo[b]thiophene-2-carboxylate derived ratiometric Schiff base fluorescent sensor R was devised and synthesized. R exhibited a highly sensitive and selective ratiometric response to In3+ in DMF/H2O tris buffer solution. R exhibited a colorimetric/fluorescent dual-channel response to In3+. More importantly, R can distinguish In3+ from Ga3+ and Al3+ in less than 5min. R exhibited a good linear correlation with the concentration of In3+ in the 5-25μM range and the limit of detection for In3+ was found to be 8.36 × 10-9M. According to the job`s plot and MS spectra, R formed a complex with In3+ at 1:2 with a complexation constant of 8.24 × 109 M2. Based on Gaussian theory calculations, the response mechanism of R to In3+ can be explained by photo-induced electron transfer (PET) and intramolecular charge transfer (ICT) mechanisms. In addition, R can be used for the detection of indium in tap water with satisfactory recoveries. Meanwhile, R displayed a linear relationship to micromolar concentrations (0-50μM) of Pb2+ and recognized Pb2+ in a ratiometric response with a detection limit of 8.3 × 10-9M.

Solvatochromism of new tetraphenylethene luminogens: integration of aggregation-induced emission and conjugation-induced rigidity for emitting strongly in both solid and solution state.

In this study, we synthesized and characterized four tetraphenylethene (TPE) analogs, investigated their photophysical properties, and conducted quantum chemical calculations. Some molecules exhibited aggregation-induced emission enhancement behavior and showed efficient emission in both solid and solution states. Solvatochromism was observed in particular derivatives, with solvent polarity influencing either a bathochromic or hypsochromic shift, indicating the occurrence of photoinduced intramolecular charge transfer (ICT) processes. Quantum chemical calculations confirmed that variations in molecular packing and rigidity among the TPE analogs contributed to their diverse behavior. The study showcases aggregation in luminophores without significant impact on the excited state and highlights how minor alterations in terminal substituents can lead to unconventional behavior. These findings have implications for the development of luminescent materials. Furthermore, the synthesized compounds exhibited biocompatibility, suggesting their potential for cell imaging applications.

Photo-induced Intramolecular Charge Transfer in Strained Organic Cage Containing Orthogonally Arranged Donors and Acceptors

Photo-induced Intramolecular Charge Transfer in Strained Organic Cage Containing Orthogonally Arranged Donors and Acceptors

Theoretical Investigation on the "ON-OFF" Mechanism of a Fluorescent Probe for Thiophenols: Photoinduced Electron Transfer and Intramolecular Charge Transfer.

In this study, the sensing mechanism of (2E,4E)-5-(4-(dimethylamino)phenyl)-1-(2-(2,4dinitrophenoxy)phenyl)penta-2,4-dien-1-one (DAPH-DNP) towards thiophenols was investigated by density functional theory (DFT) and time-dependent DFT (TD-DFT). The DNP group plays an important role in charge transfer excitation. Due to the typical donor-excited photo-induced electron transfer (d-PET) process, DAPH-DNP has fluorescence quenching behavior. After the thiolysis reaction between DAPH-DNP and thiophenol, the hydroxyl group is released, and DAPH is generated with the reaction showing strong fluorescence. The fluorescence enhancement of DAPH is not caused by an excited-state intramolecular proton transfer (ESIPT) process. The potential energy curves (PECs) show that DAPH-keto is less stable than DAPH-enol. The frontier molecular orbitals (FMOs) of DAPH show that the excitation process is accompanied by intramolecular charger transfer (ICT), and the corresponding character of DAPH was further confirmed by hole-electron and interfragment charge transfer (IFCT) analysis methods. Above all, the sensing mechanism of the turn-on type probe DAPH-DNP towards thiophenol is based on the PET mechanism.

Solvent Effect on the Photoinduced Intramolecular Charge-Transfer and Redox Potentials of Three Difuranones.

We report solvent-dependent excited state properties of three difuranone derivatives with a quinoidal backbone by steady-state and lifetime fluorescence measurements and theoretical calculations. Remarkable bathochromic shifts in fluorescence with diminished intensity indicate the occurrence of strong intramolecular charge-transfer transitions in high polar solvents. Cyclic voltammetric redox potentials reveal an interesting variation of biradical characters of the compounds with increasing solvent polarity. Solvent polarity also significantly modulates the energy levels of the charge-transfer (CT) states, as observed from the combined analyses of redox potentials and photophysical data via the Rehm-Weller equation. When high polar solvents favor forward CT by a more exoergic driving force and stabilize the charge-separated states, the reverse CT process diminishes. Estimated free energies of activation for CT suggest that high polar solvents lessen the activation barrier. Calculated excited state energies of the compounds at the CAM-B3LYP/6-31+G* level fulfill the primary conditions required for singlet fission, a process that can substantially increase the efficiency of solar cells, and the crystal packing for compound 1 also reveals a favorable geometry for singlet fission.

Nonlinear Optical Responses of Photoswitchable Donor–Acceptor Stenhouse Adducts

This work combines hyper-Rayleigh scattering (HRS) experiments performed in the NIR range (1.30 and 1.60 μm) and quantum chemical calculations to provide a comprehensive description of the second harmonic generation (SHG) responses of donor-acceptor Stenhouse adducts (DASAs). Representative derivatives of the three generations of DASAs, which differ by the nature of their electron-donating and withdrawing moieties and also include clickable species, have been synthesized and their photoswitching behavior fully characterized. The HRS measurements allow us to establish relationships between the magnitude of the SHG response of open forms and the nature of the donor and acceptor groups. The largest SHG responses are obtained for derivatives incorporating either a barbituric acid or an indanedione acceptor unit, while N-methylaniline appears as the most efficient donor group. The calculations support well the experimental data and show that high hyperpolarizabilities are associated to low excitation energies and large extent of the photoinduced intramolecular charge transfer, which enhances the dipole moment variation between the ground and first dipole-allowed electronic excited state. In addition, a complete investigation of the photoswitching kinetics of DASAs in chloroform solution shows important differences, highlighting in particular the role of the donor group on the photoswitching efficiency.

Significant acceleration of E-Z photoisomerization induced by molecular planarity breaking

E-Z photoisomerization constitutes the footstone of photosensitive proteins, molecular photoswitches and sunscreens and is believed to be controlled by photoinduced intramolecular charge transfer. In this work, we have made methylation on isomerizable alkene bond of plant sunscreen sinapate esters to break the coplanarity between phenol ring and CC double bond in ground state. Femtosecond transient absorption spectroscopy combined with time-dependent density functional theory calculations determine that this molecular planarity breaking triggers an immediate excited-state CC double bond twisting and thus accelerates the isomerization by more than one order of magnitude. These results highlight the role of molecular geometry on isomerization dynamics.

Enabling Peculiar Photophysics and Mechanochromic Luminescence by Introducing Bromine in Push–Pull Pyridine Derivatives

Pyridine-based derivatives Py-1, Py-2, and Py-3 were synthesized by the Suzuki cross-coupling reaction, and the effect of different substituents at the ortho position of the pyridine ring was investigated. In the molecular framework of push–pull compounds, electron acceptor (A) pyridine was substituted with an electron donor (D) dimethoxy triphenylamine unit. The effect of passing from a dipolar (D-A, Py-1) to a quadrupolar (D-A-D, Py-3) structure as well as the impact of functionalizing the pyridine with a bromine in the dipolar structure (D-A-Br, Py-2) was investigated. All the pyridine derivatives were found to be highly emissive both in solution and in the solid state, with fluorescence properties markedly sensitive to the environment and responsive to external stimuli. The spectral and photophysical properties in solution were investigated through conventional steady-state and advanced time-resolved spectroscopies with nanosecond and femtosecond temporal resolution. The expected efficient intersystem crossing for the heavy-atom-containing molecule was surprisingly not highlighted by our experiments, but an increased push–pull character was enabled by functionalizing the pyridine acceptor with the bromine. The ultrafast spectroscopic study revealed a peculiar excited state deactivation mechanism for the Br derivative among the others, involving photoinduced intramolecular charge transfer accompanied by twisting of the molecular structure (population of a TICT excited state). Similarly, a significant color change in the solid-state emission was observed for Py-2 upon mechanical grinding, suggesting a mechanochromic luminescence behavior in this case. Our findings suggest introducing heavy atoms in organic fluorophores as a new design strategy to obtain mechanoluminescent materials.

Axial vs equatorial: Capturing the intramolecular charge transfer state geometry in conformational polymorphic crystals of a donor-bridge-acceptor dyad in nanosecond-time-scale.

Two conformational polymorphs of a donor-bridge-acceptor (D-B-A) dyad, p-(CH3)2N-C6H4-(CH2)2-(1-pyrenyl)/PyCHDMA, were studied, where the electron donor (D) moiety p-(CH3)2N-C6H4/DMA is connected through a bridging group (B), -CH2-CH2-, to the electron acceptor (A) moiety pyrene. Though molecular dyads like PyCHDMA have the potential to change solar energy into electrical current through the process of photoinduced intramolecular charge transfer (ICT), the major challenge is the real-time investigation of the photoinduced ICT process in crystals, necessary to design solid-state optoelectronic materials. The time-correlated single photon counting (TCSPC) measurements with the single crystals showed that the ICT state lifetime of the thermodynamic form, PyCHDMA1 (pyrene and DMA: axial), is ∼3ns, whereas, for the kinetic form, PyCHDMA20 (pyrene and DMA: equatorial), it is ∼7ns, while photoexcited with 375nm radiation. The polymorphic crystals were photo-excited and subsequently probed with a pink Laue x-ray beam in time-resolved x-ray diffraction (TRXRD) measurements. The TRXRD results suggest that in the ICT state, due to electron transfer from the tertiary N-atom in DMA moiety to the bridging group and pyrene moiety, a decreased repulsion between the lone-pair and the bond-pair at N-atom induces planarity in the C-N-(CH3)2 moiety, in both polymorphs. The Natural Bond Orbital calculations and partial atomic charge analysis by Hirshfeld partitioning also corroborated the same. Although the interfragment charge transfer (IFCT) analysis using the TDDFT results showed that for the charge transfer excitation in both conformers, the electrons were transferred from the DMA moiety to mostly the pyrene moiety, the bridging group has little role to play in that.

Multi-parametric sensing by multi-channel molecular fluorescent probes based on excited state intramolecular proton transfer and charge transfer processes

Considering the applications of fluorescent probes and the information they provide, their brightness of fluorescence and photostability are of paramount importance. However, in the case of steady-state fluorescence spectroscopy and fluorescence microscopy, the amount of information can be increased by the application of multi-channel probes, via a multi-band fluorophore introduced in the probe molecule. In most cases, the use of such a multi-band (or multi-channel) fluorophore can also be combined with the concomitant introduction of one or several analyte receptors. Most often, the design of ratiometric probes with multi-band fluorescence emission are based on phenomena such as photoinduced intramolecular charge transfer (ICT) or excited state intramolecular proton transfer (ESIPT). Although ICT probes were up to recently the most popular, ESIPT probes and among them 3-hydroxyflavone derivatives, were shown to be the most productive. Several general problems were resolved by this family of probes, as for example the measurement of local dielectric constant, local H-bond accepting ability, water local concentration and ATP concentration in small volumes.Incorporation of such multi-channel probes into lipid membranes allowed to measure the different membrane potentials and to detect cell apoptosis. Also, it enabled to recognize and characterize the rafts formation in different lipid bilayers and peculiar features of the charged membrane interface. Such probes are also able to provide a concentration-dependent fluorescence signals upon binding of H+, Mg2+and Ba2+ions, and thus to recognize these different cations.The multi-channel probes are effective tools in the study of interactions of macromolecules such as peptides, proteins and nucleic acids. The most useful feature is that they inform simultaneously about several physical parameters, in this way giving a better insight in the investigated system. Thus, by comparing the reviewed probes with other modern fluorescent approaches, it can be concluded they are more informative and accurate tools.

Fluorescent "AND" logic gates for simultaneous detection of thiols and protons: photophysical properties, mechanism and bioimaging of living cells.

Five fluorescent probes TP1-5 were demonstrated as two-input "AND" molecular logic gates for the detection of thiols and protons. The molecules were designed based on "thiol receptor-spacer1-fluorophore-spacer2-proton receptor" mode. The logic gates were constructed by employing maleimide, naphthalimide and morpholine (TP1-3)/N-methyl piperazine (TP4-5) as the thiol receptor, fluorophore and proton receptor, respectively. All probes show significant fluorescence enhancements upon addition of both protons and thiols. However, much weaker spectral responses were observed with the addition of only one single analyte. The fluorescence outputs, based on photoinduced electron transfer (PET) and (twisted) intramolecular charge transfer (TICT/ICT), were modulated by the proton receptor and linker. The length of spacer1 affects the responses toward thiols, whereas spacer2 influences the sensing performance toward protons. The difference between the pKa values of morpholine (∼5.80) and N-methyl piperazine (∼7.10) enables us to detect thiols in divergent pH circumstances. TP1-3 exhibit an excellent "AND" logic function for simultaneous detection of protons and thiols as well as bioimaging thiols in weakly acidic living cells. However, TP4 and TP5 are not good candidates for executing "AND" logic operation possibly due to the stronger electron donating properties and steric effect of N-methyl piperazine.

C–O Bond Activation in Mononuclear Lanthanide Oxocarbonyl Complexes OLn(η2-CO) (Ln = La, Ce, Pr, and Nd)

Fundamental investigation of metal-CO interactions is of great importance for the development of high-performance catalysts to CO activation. Herein, a series of side-on bonded mononuclear lanthanide (Ln) oxocarbonyl complexes OLn(η2-CO) (Ln = La, Ce, Pr, and Nd) have been prepared and identified in solid argon matrices. The complexes exhibit uncommonly low C-O stretching bands near 1630 cm-1, indicating remarkable C-O bond activation in these Ln analogues. The η2-CO ligand in OLn(η2-CO) can be claimed as an anion on the basis of the experimental observations and quantum chemistry investigations, although the CO anion is commonly considered to be unstable with electron auto-detachment. The CO activation in OLn(η2-CO) is attributed to the photoinduced intramolecular charge transfer from LnO to CO rather than the generally accepted metal → CO π back-donation, which conforms to the traditional Dewar-Chatt-Duncanson motif. Energy decomposition analysis combined with natural orbitals for chemical valence calculations demonstrates that the bonding between LnO and η2-CO arises from the combination of dominant ionic forces (>76%) and normal Lewis "acid-base" interactions. The fundamental findings provide guidelines for the catalyst design of CO activation.

Photophyical and photosensitizing properties of BODIPYs substantially changed by alkyl- and phenyl-amino groups on meso carbon

meso-RNH (R = C3H7, C4H9, PhCH2, H, and Ph) substituted BODIPY compounds have been prepared to examine their photophysical properties and photosensitizing abilities. We have measured the UV–vis absorption, steady state and time resolved fluorescence, excited triplet state formation using laser flash photolysis, singlet oxygen generation ability using chemical trapping method. The results show that the presence of meso-RNH leads to large blue shift of absorption and emission wavelength, remarkable decrease in fluorescence quantum yield and lifetime values, and significant increase in singlet oxygen formation quantum yield. Quantum chemical calculation also reveals the photoinduced charge transfer (PCT) mechanism. We conclude that property changes are due to: 1) S0 and S1 geometry, 2) ground state structural isomerization, and 3) intramolecular PCT. These results and mechanisms are helpful for designing new functional materials.

Unraveling photo-induced proton transfer mechanism and proposing solvent regulation manner for the two intramolecular proton-transfer-site BH-BA fluorophore

To expound specific excited state processes of the novel excitation wavelength dependent emission BH-BA fluorophore for better subsequent applications, this wok mainly focus on exploring photo-induced hydrogen bonding geometrical changes, excited state intramolecular proton transfer (ESIPT) mechanism and related regulated behavior via solvent polarity. The differences of structural parameters, infrared (IR) vibrational spectra, core-valence bifurcation (CVB) index as well as electronic densities ρ(r) between S0 and S1 states related to dual hydrogen bonds (O1-H2···N3 and O4-H5···N6) reveal S1-state hydrogen bonding strength facilitate ESIPT behaviors for BH-BA system. Of particular note, O4-H5···N6 plays a more dominant role. Photo-induced intramolecular charge transfer (ICT) and variations of Hirshfled and NPA charges over atoms related to hydrogen bonding moieties promote the ESIPT tendency for BH-BA. Combined potential energy surfaces (PESs), transition state (TS) and intrinsic reaction coordinate (IRC) paths, we illustrate the excited state intramolecular single proton transfer (ESISPT) mechanism of BH-BA should occur along with O4-H5···N6 hydrogen bonding wire, which could be adjusted by surrounding solvent polarity.

Charge Transfer Chromophores Derived from 3d-Row Transition Metal Complexes

A series of new charge transfer (CT) chromophores of "α-diimine-MII-catecholate" type (where M is 3d-row transition metals-Cu, Ni, Co) were derived from 4,4'-di-tert-butyl-2,2'-bipyridyl and 3,6-di-tert-butyl-o-benzoquinone (3,6-DTBQ) in accordance with three modified synthetic approaches, which provide high yields of products. A square-planar molecular structure is inherent for monomeric [CuII(3,6-Cat)(bipytBu)]∙THF (1) and NiII(3,6-Cat)(bipytBu) (2) chromophores, while dimeric complex [CoII(3,6-Cat)(bipytBu)]2∙toluene (3) units two substantially distorted heteroleptic D-MII-A (where D, M, A are donor, metal and acceptor, respectively) parts through a donation of oxygen atoms from catecholate dianions. Chromophores 1-3 undergo an effective photoinduced intramolecular charge transfer (λ = 500-715 nm, extinction coefficient up to 104 M-1·cm-1) with a concomitant generation of a less polar excited species, the energy of which is a finely sensitive towards solvent polarity, ensuring a pronounced negative solvatochromic effect. Special attention was paid to energetic characteristics for CT and interacting HOMO/LUMO orbitals that were explored by a synergy of UV-vis-NIR spectroscopy, cyclic voltammetry, and DFT study. The current work sheds light on the dependence of CT peculiarities on the nature of metal centers from various groups of the periodic law. Moreover, the "α-diimine-MII-catecholate" CT chromophores on the base of "late" transition elements with differences in d-level's electronic structure were compared for the first time.

Vis–NIR Electrochromism and NIR–Green Electroluminochromism in Dual Functional Benzothiadiazole‐Arylamine Mixed‐Valence Compounds

AbstractElectrochromism/electrofluorochromism is the reversible tuning of the absorption/photoluminescence by redox processes. Dual functional electrochromic/electrofluorochromic materials can be exploited in, for example, smart windows, encryption/anticounterfeiting technologies, displays, and biomedical sensors. While electrofluorochromic materials showing tunable fluorescence intensity are relatively widespread, those with tunable color emission are not. Moreover, electrofluorochromic materials with tunable emission in the near‐infrared (NIR) range are seldom encountered. Here, this work shows a new molecular approach to afford both the above functionalities, in addition to red–NIR electrochromism, by combining the properties of highly stable arylamine radical cation mixed valence species, with those of donor–acceptor systems exhibiting the photoinduced twisted intramolecular charge transfer mechanism.

Tris(trifluoromethyl)germyl biphenyl conjugated molecular system with ferrocenyl substituent: Confirmation of photoinduced intramolecular charge transfer to the germanium center

Unsymmetrical 4,4′-biphenyl derivative with tris(trifluoromethyl)germylethynyl ‒CC‒Ge(CF3)3 and ferrocenylethynyl Fc‒CC‒ substitutes have been prepared (21), its properties have been studied and compared with those full non-fluorinated analogue of trimethylgermylethynyl ‒CC‒Ge(CH3)3 compound (20). UV-visible, absorption, steady state, and time-resolved fluorescence spectra in solution for these germanium and a number of similar compounds (15-17, 22) have been investigated. The process of photoinduced electron transfer from the π-conjugated system to the germanium center is confirmed for 21, as well as for the first time discovered earlier [19] in the 4-biphenyl ‒CC‒Ge(CF3)3 molecule (9). It was found that the lifetime of the radical-ion pair 21 in the excited state (kCR2 = 1.2 × 105 s-1) is approximately an order of magnitude longer than for 9, which can be explained by the stabilizing effect of the electron donor Fc‒CC‒ group. Density-functional theory (DFT) computations was used to calculate the optimized geometry of 21 in excited state, and two main bands in the emission spectrum at laser excitation (340 and 386 nm) an excellent fit to the experimental data. An additional data on the nature of the (CF3)3Ge group, including geometry, electronegativity, and contributions 4d AOs of germanium into lowest unoccupied molecular orbital (LUMO) in a wide range of fluorinated and non-fluorinated compounds were also calculated. The molecular structure of compound 21 was determined by X-ray structural analysis. In the crystal lattice of 21, numerous intermolecular F‧‧‧F interactions shortened in comparison with the van der Waals radii were detected, which leads to the formation of quasi-two-dimensional fluorinated layers in crystals.

Effect of cyano substituent on the functional properties of blue emitting Imidazo[1,2-a]pyridine derivatives

High fluorescence efficiency and balanced charge transportation in organic emitters are desirable characteristics for application in OLEDs. Generally, donor-acceptor compounds showing pronounced intramolecular charge transfer exhibit low fluorescence quantum yield. Here, we report D-A fluorophores containing CN-substituted 2-phenylimidazo[1,2-a]pyridine acceptor unit which exhibit good fluorescence characteristics. The positions of donors (triphenylamine/carbazole) and cyano substituents are respectively interchanged to get a series of isomers. All the fluorophores exhibit high fluorescence quantum yield (Фf≥ 0.70) and excellent thermal stability (Td10≥ 390 °C). A dye comprising triphenylamine unit at para-position of C2 phenyl ring exhibited red-shifted emission maxima with larger Stokes shift in the series. Moreover, all the isomers displayed excited-state solvatochromism attributable to the photo-induced intramolecular charge transfer between donors and cyano-imidazo[1,2-a]pyridine acceptor. Addition of the cyano group on imidazopyridine restrained the formation of aggregates in the solid-state and stabilized the lowest unoccupied molecular orbital. Among the all, doped devices constructed with 3 wt% of triphenylamine containing dye revealed excellent performance in the series with a maximum EQE of 6.9%, 2759 cd/m2 luminance, and CIE coordinates (0.16, 0.08) which is very close to the NTSC blue standard.

Indolo[3,2,1-jk]carbazole-Derived Narrowband Violet-Blue Fluorophores: Tuning the Optical and Electroluminescence Properties by Chromophore Juggling.

The development of rigid polyaromatic building blocks for narrowband violet fluorophores has received tremendous attention. Herein, we designed and synthesized two new triangle-shaped rigid building blocks, namely, 2,5-di-tert-butylindolo[3,2,1-jk]carbazole (tBuICz) and 2,11-di-tert-butylindolo[3,2,1-jk]carbazole-4-carbonitrile (tBuICzCN), and tethered them with different chromophores to yield a series of violet-blue fluorophores, viz., ICzTPA-ICzPICN, and studied their structure-function relationship. The appended chromophores and cyano unit played a vital role in controlling the optical and electrical properties of the compounds. Except triphenylamine-substituted derivatives, the compounds showed pure violet emission (λem ≤ 403 nm). Intriguingly, the compounds exhibited narrow-band emission with a full-width at half-maximum ≤ 40 nm, attributed to the rigidity of the ICz core. The emission of the compounds displayed positive solvatochromism, which is ascribed to the photoinduced intramolecular charge transfer in the excited state. The compounds revealed excellent thermal robustness with T5d ≥ 363 °C. The triphenylamine-featuring derivatives displayed a high-lying HOMO compared to their congeners due to their electron-rich nature. When we applied these materials in organic light-emitting diodes, ICzPI outperformed in the series with an EQEmax of 3.07% and a current efficiency of 1.04 cd/A. Notably, its CIEy ∼ 0.046 precisely matched with the Rec.2020 standard of deep-blue color (CIEy ∼ 0.046).