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The preparation of a new zinc(II) metalloporphyrin, substituted with four alkylated carbazole moieties, by reaction of pyrrole and 3-formyl-9-hexylcarbazole is reported. The substitution pattern negatively shifts the redox potentials of the macrocycle and leads to a material that emits green light at 615 nm when photo-excited at 554 nm.

Four different types of alternating copolymers, named as poly(N-(2-ethylhexyl)-3,6-dibromo-carbazole-alt-aniline) (P1), poly(3,6-dibromo-carbazole-alt-aniline) (P2), poly(N-(3,5-dibromo-methylene-phenyl)-carbazole-alt-aniline) (P3) and poly(N-[4-(2-ethylhexyloxyl)-3,5-dibromomethylene-phenyl]-carbazole-alt-aniline) (P4) were successfully synthesized by palladium-catalyzed polycondensation of corresponding carbazole-containing dibrominated compounds and an aniline. These resulting polymers exhibited good solubility in normal organic solvents and showed relatively high molecular weights. Excellent thermal stability of the polymers was observed from TGA, showing less than 8% of weight loss on heating to 350°C under N₂ atmosphere. From UV-Vis absorption and photoluminescence spectra of these solution-processable polymers, it was observed that λ_max,UV was in the range of 308 – 352 nm and λ_max,PL was in the blue emission range of 450 – 463 nm. Electrochemical characteristics of these alternating copolymers were investigated to prove the potential in application for blue-emitting host matrix and hole-transporting layer in polymer light-emitting devices.

A series of random copolymers of 2,7-dibromo-9,9-bis(4′-n-octyloxyphenyl) fluorene (BOPF) and 2,7-dibromo-N-(2′-ethylhexyl)carbazole (EHC) were synthesized through Ni(0)-mediated polymerization. Carbazole comonomer was introduced to improve the hole-transporting properties of PBOPF. The synthesized poly(BOPF-co-EHC)s showed similar UV-visible absorption and PL emission to PBOPF. EL devices were fabricated in an ITO/PEDOT/polymer/Ca/Al configuration. EL devices which used copolymers showed improved device performance over devices which used PBOPF homopolymers due to a more balanced charge transport.

We synthesized and characterized novel highly phenyl-substituted spirobifluorene and carbazole derivatives such as 3,6-bis[(2,3,4,5-tetraphenyl)phenyl]-9-ethylcarbazole (BTPEC); 3,6-bis(7,10-diphenyl-fluoranthene)-9-ethylcarbazole (BDFEC); 2,7-Bis[(2,3,4,5-tetraphenyl)phenyl]-9,9′-spirobifluorene (BTPSF); and 3,6-bis(7,10-diphenyl-fluo-ran-thene)-9,9′-spirobifluorene (BDFSF), through Diels–Alder reaction. BDFEC showed sky blue PL spectrum at 481 nm and BTPSF showed ultra-violet PL spectrum at 374 nm in chloroform solution. Also BTPEC and BDFSF exhibited PL spectrum at around the UV region, 390 and 467 nm.

Polyazomethine-type conjugated polymers were synthesized by Schiff-base reaction. One was poly(PZ-PBI) with alternating phenothiazine (PZ) and azomethine units (-C = N-), and the other was poly(CZ-PBI) comprising alternating carbazole (CZ) and azomethine groups. Conjugated polymers exhibited improved solubility in common organic solvents due to alkyl side chains on phenothiazine and carbazole rings as well as polar azomethine groups in main chains. Single- and double-layer PLEDs were fabricated. Their electroluminescent properties were studied from the viewpoint of polymer structure vs. emission color and efficiency.

Derived from diarylamine sensitizer diphenyl-(7-pyridin-4-yl-9H-carbazol-2-yl)-amine (N13), a series of novel D$-\pi -$A carbazole-based organic dye sensitizers with different $\pi$-linkers were designed for searching more effective sensitizers in dye-sensitized solar cells (DSSCs) design. Optimized geometries, electronic structure, and other parameters, which can evaluate the performance of DSSCs effectively and intuitively, were theoretically calculated by density functional theory (DFT) and time-dependent DFT methods at the M06/6-31G(d,p) level. The results indicated that the maximum absorption wavelength of designed dye was red-shifted and the molar absorption coefficient ($\epsilon$) became higher. This phenomenon can be explained by the modification of the $\pi$-bridge. The simulated Ultraviolet–visible spectroscopy (UV-Vis) absorption spectrum showed that the designed N,N-diphenyl-7-(5-(7-(5-(pyridin-4-yl)thiophen-2-yl)benzo[c][1,2,5]thiadiazol-4-yl)thiophen-2-yl)-9H-carbazol-2-amine (N22) dye presents the largest red-shifted absorption band and the designed (E)-N,N-diphenyl-7-(2-(5${}^{\prime }$-(pyridin-4-yl)-[2,2${}^{\prime }$-bithiophene]-5-yl)vinyl)-9H-carbazol-2-amine (N21) dye showed the largest $\epsilon$, both of them depicted a high short-circuit photocurrent density ($J_{\mathrm{\text{sc}}})$. Meanwhile, the charge separation hampered by long $\pi$-linkers was also observed. These results are helpful for designing new sensitizers and providing effective guiding to experimental synthesis.

A series of polymers bearing azobenzene and carbazole groups for photorefractive purpose were prepared via post-azo-coupling reaction. The successful reaction was identified by spectroscopic analysis and gel permeation chromatography. This approach is more facile compared with the direct polymerization of corresponding functional monomer. The polymers prepared have weight average molecular weight of higher than 1.5×10⁴ and are easily soluble in common organic solvents like chloroform and tetrahydrofuran, polymer films with high optical quality could be easily fabricated through solution casting. Glass transition temperature (T_g) of the polymers ranges from 60°C to 182°C, depending on the alkylene spacer length between the functional side group and the polymer backbone, and the polymers are relatively stable under 300°C.

New hyperbranched poly(aryleneethynylene)s containing carbazole moieties are synthesized in high yields (up to 87%) by polycyclotrimerization of 3,6-bis(4-ethynylphenyl)-9-octylcarbazole and its copolymerization with 1-octyne catalyzed by CpCo(CO)₂ in THF. The structures and properties of the polymers are characterized and evaluated by IR, NMR, TGA, UV, photoluminescence, and cyclic voltammetry analyses. All the polymers are soluble in common organic solvents and show outstanding thermal stability (≥ 430°C). They graphitize in high yields (up to 79%) when pyrolyzed at 800°C. Upon photoexcitation, the polymers emit a strong deep blue light of ca. 400 nm with quantum yields larger than 60%.

A new luminescent and thermally stable platinum(II) polyyne polymer trans-[–Pt(PBu₃)₂C≡CArC≡C–]_n (P1) containing the 2,7-fluorene chromophoric spacer substituted by pendant carbazolyl group via long alkyl bridges. The regiochemical structures of these compounds were studied by various spectroscopic analyses. We report the photophysical properties of this group 10 polymetallayne and a comparison was made to its binuclear model complex trans-[Pt(Ph)(PEt₃)₂C≡CArC≡CPt(Ph)(PEt₃)₂] (M1) as well as to those with non-carbazole-containing fluorene spacer (P2 and M2). Upon photoexcitation, each of P1 and M1 emits an intense purple-blue fluorescence emission in the near-UV to visible region in dilute fluid solutions at room temperature. Harvesting of organic triplet emissions harnessed through the strong heavy-atom effects of platinum metal was examined and at 77 K, each of the metalated compounds displayed dual emission bands, viz. both the fluorescence and the lower-lying phosphorescence. Spectroscopic results revealed that the formation of excimers was suppressed by introducing carbazole side groups. The spatial extent of the lowest singlet and triplet excitons in P1 and M1 was fully elucidated. Such organometallic poly(fluorenyleneethynylene)s anchored with the carbazole pendants was found to have an improved thermal stability and suppressed aggregation.

Novel 9-proparylcarbazole monomers containing amino acid moieties, 2-N-(tert-butoxycarbonyl)-L-alanine-9-proparylcarbazole ester (1), 2-N-(tert-butoxycarbonyl)-L-O-cyclohexyl-L-glutamic acid-9-proparylcarbazole ester (2) and 2-N-(tert-butoxycarbonyl)-L-phenylalanine-9-proparylcarbazole ester (3) were synthesized and polymerized with (nbd)Rh⁺ [η⁶-C₆H₅B^–(C₆H₅)₃] to give the corresponding polymers with number-average molecular weights ranging from 7050 to 10500 in 70%–86% yields. The polymers were completely soluble in toluene, CHCl₃, CH₂Cl₂, THF and DMSO, but insoluble in hexane, diethyl ether and MeOH. The specific rotation studies revealed that poly(1)–poly(3) do not took predominantly one-handed helical structures in the solvents although they possess chiral groups. The polymers emitted fluorescence in 0.40%–2.35% quantum yields. The cyclic voltammograms of the polymers indicated that the polymers exhibited electrochemical properties.

A new subporphyrin namely, hydroxo-5,10,15-tri($N$-propyl-3-carbazolyl)subporphyri natoboron(III) 6 has been synthesized via the reported litreture procedure by the condensation of pyridine-tri-$N$-pyrrolylborane with 9-propyl-9H-carbazole-3-carbaldehyde. Its porphyrin analog $i.e$. 5,10,15,20-tetra($N$-propyl-3-carbazolyl)porphyrin has also been isolated from the reaction mixture, formed due to scrambling process and complexed with Zn(II). Photophysical properties of both subporphyrin and Zn(II)porphyrin have been studied in detail to confirm the intramolecular charge transfer process in subporphyrin analog. In addition, the ring contracted congener 6 also displays solid state fluorescence.

Novel octa-phenotiazine, octa-benzoazepine and octa-carbazole substituted magnesium(II) (MgPz-I-III) and zinc(II) (ZnPz-I-III) porphyrazines were synthesized from 2,3-bis[6-(4a,10a-dihydro-phenothiazin-10-yl)-hexylsulfanyl]-but-2-enedinitrile (5), 2,3-bis [6-(4a,11a-dihydro-dibenzo[b,f]azepin-5-yl)-hexysulfan-yl]-but-2-enedinitrile (8) and 2,3-bis(6-carbazol-9-yl-hexylsulfanyl)-but-2-enedinitrile (10), respectively. These dinitrile derivatives 5, 8 and 10 were also prepared by the reaction of 1,2-dicyano-1,2-ethylenedithiolate di-sodium salt (4) with 10-(6-bromohexyl)-10H-phenothiazine (3), 5-(6-bromohexyl)-5H-diben-zo[b,f]azepine (7) and 9-(6-bromo-hexyl)-9H-carbazole (9), respectively. Porphyrazino-zinc(II) complexes were synthesized by one-step reaction using Zn(BuO)${}_{\mathrm{\text{2}}}$ as a template agent. All the novel compounds were characterized by elemental analysis and different spectroscopic methods such as ${}^{\mathrm{\text{1}}}$H NMR, ${}^{\mathrm{\text{13}}}$C NMR, FT-IR, UV-Vis and mass. The photochemical properties including photodegradation and singlet oxygen generation for magnesium(II) and zinc (II) porphyrazine complexes were studied in dimethylsulfoxide solutions for determination of their photosensitizer behaviors.

Porphyrins are tetrapyrrolic aromatic macrocycles and ubiquitous in nature. They are excellent dyes with strong absorption in the visible region (400–700 nm) and they exhibit decent fluorescence in the red region (620–900 nm). Carbazole is a nitrogen-containing electron rich aromatic heterocycle which can be linked to porphyrins and other chromophores. This review provides an overview of the different synthetic strategies that have been employed to prepare carbazole-substituted porphyrins and carbazole-fused porphyrinoids and similar systems. It also shows that how the substitution of carbazole occurs on the porphyrin core can alter its optical and electronic features. Introduction of carbazole moieties in the porphyrin ring resulted in fused porphyrinoids with changed aromaticity and significantly altered electronic features of the molecules.

Chiral carbazole-based porphyrins were synthesized for the first time via the incorporation of hydrobenzoin units at the thiophene moieties. They showed absorption and circular dichroism in the near-infrared (NIR) region. The NIR absorption was further red-shifted by solvent-induced aggregation.

We report two corrole based donor–acceptor (D–A) dyads, Cbz-Cor and Ptz-Cor to understand the energy/electron transfer reactions. In these D–A systems, the donor, either carbazole (Cbz) or phenothiazine (Ptz), is covalently connected at the meso-phenyl position of 10-(phenyl)-5,15-bis-(pentafluorophenyl)corrole (Ph-Cor) by C–N linkage. Both the dyads were characterized by ¹H NMR, MALDI-TOF MS, UV-vis, electrochemical, computational methods, study state fluorescence and TCSPC techniques. A comparison of absorption spectra with their reference monomeric compounds (Cbz-Ph, Ptz-Ph and Ph-Cor) revealed minimal ground-state interactions between chromophores in both dyads. Fluorescence studies suggested that singlet–singlet energy transfer from ¹Cbz* to corrole is the major photochemical pathway in the Cbz-Cor dyad with a quenching efficiency of $\sim$99%. Detailed analysis of the data suggests that Forster’s dipole–dipole mechanism does not adequately explain this energy transfer. However, at a 410 nm excitation, florescence quenching is detected in Ptz-Cor (49%) supporting a photo induced electron transfer (PET) process from the ground state of PTZ to the excited state of corrole macrocycle. The electron-transfer rates ($k_{ET})$ of Ptz-Cor are found in the range $0.6\times 10^7$ to $1.24\times 10^8{\mathrm{\text{s}}}^{-1}$ and are concluded to be solvent dependent.

Amphiphilic carbazole pyridinium conjugates are synthesized and characterized by IR, ¹H and ${}^{13}$C NMR and ESI-MS spectrometry. The pyridinium group is attached on the 3-position of the carbazole ring and long alkyl chains are linked to the central $N$ atom. The introduction of a pyridinium group afforded water-soluble carbazole derivatives with significant bathochromic shifts in their absorption and emission spectra. As compared to the parent $N$-butylcarbazole compound, carbazole pyridinium conjugates exhibited 50 nm red-shifted absorption maxima. Similarly, the carbazole pyridinium conjugates displayed 143–147 nm red-shifted emission maxima in solution. In addition, large Stokes shifts (5747–7558 cm${}^{-1})$ were observed for the conjugates in solution. The cell penetrable amphiphilic carbazole pyridinium conjugates exhibited cytoplasmic distribution in A549 cells.

As a new family of porphyrinoids with broad absorption bands that efficiently harvest sunlight, the metal complexes of a porphyrin quadruply substituted with $N$-carbazolyl groups at the meso positions were photometrically and structurally characterized. The porphyrins exhibited characteristic broad bands in the range of 450–500 nm, due to the charge transfer band from carbazole to porphyrin. Ligand exchange at the axial position of the zinc complex with an aquo ligand affected the absorption spectrum, and a hyper-hypsochromic shift of the broad band was observed by the coordination of methanol. Furthermore, the lowest unoccupied molecular orbital (LUMO) levels of the metalloporphyrins were lowered by the electron-withdrawing effect of the perpendicularly oriented carbazolyl groups. In the solid state, zinc-porphyrin was self-assembled into a one-dimensional coordination polymer by intermolecular axial coordination.

Carbazole compounds have been proven to exhibit vital photophysical and biological applications. Even simple carbazole derivatives were showing attractive biological activities such as antimicrobacterial activity (Glycozoline), antiproliferative activity (Mukonine), free radical scavenger (Carazostatin), etc. In case of photophysical applications, carbazole derivatives were utilized in organic semiconductors, photoconducting polymers, Green host material in phosphorescent organic light-emitting diodes (OLEDs), hole-transporting material in OLEDs and organic light emitting materials. An account of different synthetic methodologies involved in the synthesis of natural and synthetic carbazole derivatives was evaluated based on the usage of commercially available cheap starting materials such as derivatives of Indole. This paper takes into account the time from 2011 to 2023. The advanced methods were developed based on the 12 principles of Green chemistry such as Multistep domino reactions, Atom & Step economy reactions, protection-free reactions, mild reaction conditions, open atmosphere reactions, harmless by-products and photochemical transformations.

This research investigates characterization of low lying excitations of newly designed organic dyes for their local excited and charge transfer-related molecular switching attributes such as donor-acceptor relations against the carbazole bridge. The eight new dyes, having 4 symmetrical (Syn-A-D) and 4 antisymmetric (Anti-A-D) arrangements showed how the push-pull effect can operate to create the charge transfer phenomenon. Their absorption energies (E) for Syn dyes ranged from 2.98 eV to 4.07 eV, with corresponding wavelengths (λ_max) ranging from 304 nm to 415 nm. While for their Anti arrangements, it ranged from 1.62 eV to 3.99 eV, with corresponding λ_max values as 310-617 nm. Syn-C1 with an ionization potential (IP) of 6.59 eV and an electron affinity (EA) of 2.04 eV can be predicted to be more chemically stable compared to Anti-C2 with an IP of 5.16 eV and an EA of 3.86 eV. Syn-C also has the highest V_oc (3.24 eV) and P_max (22.35 W), indicating that it has the potential to be more chemically stable as compared to the other dyes. The findings of this research contributed to a better understanding of the molecular switching attributes of carbazole-based organic dyes, which could have implications for various applications, including optoelectronics and energy conversion devices.

Porphyrins are tetrapyrrolic aromatic macrocycles and ubiquitous in nature. They are excellent dyes with strong absorption in the visible region (400–700 nm) and they exhibit decent fluorescence in the red region (620–900 nm). Carbazole is a nitrogen-containing electron rich aromatic heterocycle which can be linked to porphyrins and other chromophores. This review provides an overview of the different synthetic strategies that have been employed to prepare carbazole-substituted porphyrins and carbazole-fused porphyrinoids and similar systems. It also shows that how the substitution of carbazole occurs on the porphyrin core can alter its optical and electronic features. Introduction of carbazole moieties in the porphyrin ring resulted in fused porphyrinoids with changed aromaticity and significantly altered electronic features of the molecules.