Photophysical Analysis of 1,10-Phenanthroline-Embedded Porphyrin Analogues and Their Magnesium(II) Complexes

Phenothiazine Embedded Dithiasmaragdyrins

Two different types of novel phenothiazine-embedded dithiasmaragdyrins containing one phenothiazine ring, two thiophene rings and two pyrrole rings connected via three meso carbons and two direct bonds in the macrocyclic framework were synthesized over the sequence of synthetic steps starting with phenothiazine. Three examples of phenothiazine-embedded dithiasmaragdyrins were synthesized by condensing appropriate phenothiazine-based pentapyrrane with pentafluorobenzaldehyde and two examples of phenothiazine sulfone embedded dithiasmaragdyrins were synthesized by condensing phenothiazine-based diol with appropriate meso-aryl dipyrromethane under mild acid-catalysed conditions. 1D&2D NMR studies revealed that the thiophene rings adopted inverted orientation in phenothiazine sulfone embedded dithiasmaragdyrins whereas in phenothiazine-embedded dithiasmaragdyrins, the thiophene rings were in normal orientation. Both types of macrocycles exhibit nonaromatic absorption features and showed panchochromic absorption features in its neutral and protonated forms. The electrochemical studies indicated that the phenothiazine-embedded dithiasmaragdyrins were more electron-rich compared to phenothiazine sulfone embedded dithiasmaragdyrins. DFT studies revealed that both types of dithiasmaragdyrins exhibit significantly distorted structures and TD-DFT studies support the experimental observations.

Advent and features of pyriporphyrinoids: an overview of a pyridine-based porphyrin analogue

Pyriporphyrinoids have recently attracted a significant proliferation of attention due to their versatile characters, which stem from structural motifs in which the pyridine moiety is involved. The evolution of pyriporphyrin chemistry revealed the subtle modifications of the macrocyclic core that tweak the electronic structure as compared to the parental macrocycle. The amendment of π-electronic organization inside the core manifests exceptional photophysical and coordination properties that cover a vast range of seemingly contradictory fields. In fundamental chemistry, the pyridine unit acts as a modulator of π-conjugated porphyrinoid systems, resulting in aromaticity swapping. From the applied chemistry perspective, these macrocycles are primarily utilized as (i) sensors, (ii) NIR absorbing photoacoustic dyes, (iii) electrochemical catalysts, (iv) singlet biradicaloid generation and (v) contributors to generate metal complexes with intriguing binding modes. Surprisingly, despite their prominence, pyriporphyrinoids are inadequately investigated, while pyridine unit-embedded calixphyrin, calixpyridinopyrrole and calixpyridine are barely reported. This review article illustrates the controlled formation of specific porphyrinic scaffolds with pyridine unit(s) and diverse functionalized heterocyclic and/or carbocyclic building block(s), and demonstrates a substantial influence on the macrocyclic properties.

Synthesis and complexes of a constrained-cavity Schiff-base dipyrrin macrocycle

A new constrained-cavity [1 + 1] Schiff-base dipyrrin macrocycle comprising an N4 donor-pocket has been synthesised by spontaneous oxidation and in situ crystallisation. Access to Fe(ii) and Zn(ii) complexes is achieved by salt elimination reactions of the lithium salt. All compounds have been characterised by NMR and UV-vis spectroscopy, X-ray crystallography, and DFT analysis.

Synthesis and Studies of Strained Fluorenophyrins

New examples of polyaromatic hydrocarbons embedded porphyrinoids named fluorenophyrins, which are fluorene-embedded porphyrins, have been readily synthesized starting with commercially available fluorene as a key precursor over a sequence of four simple synthetic steps. These new fluorenophyrin macrocycles were characterized and studied by high-resolution mass spectrometry, one-dimensional and two-dimensional nuclear magnetic resonance and absorption spectroscopies, electrochemical techniques, and density functional theory calculations. The studies indicated that the fluorenophyrins are nonaromatic, and π-conjugation in macrocycles was limited due to nonplanar arrangement of a fluorene moiety with the rest of the macrocycle.

Highly Luminescent Heavier Main Group Analogues of Boron-Dipyrromethene

The preparation and photophysical properties of two heavier main group element analogues of boron-dipyrromethene (BODIPY) chromophores are described. Specifically, we have prepared dipyrrin complexes of dichlorogallate (GADIPY) or phenylphosphenium (PHODIPY) units. Whereas cationic PHODIPY is labile, decomposing to a phosphine over time, GADIPY is readily prepared in good yield as a crystalline solid having moderate air- and water-stability. Crystallographically characterized GADIPY displays intense green photoluminescence (λ_em = 505 nm, Φ_em = 0.91 in toluene). These inaugural heavier main group element analogues of BODIPY offer a glimpse into the potential for elaboration to a panoply of chromophores with diverse photophysical properties.

Benzofuran-/Benzothiophene-Incorporated NIR-Absorbing Triphyrins(2.1.1)

Novel benzofuran-/benzothiophene-incorporated triphyrins(2.1.1) were synthesized using readily available precursors under mild reaction conditions. The X-ray structure revealed that the benzofuran-incorporated triphyrin(2.1.1) macrocycle was slightly ruffled. The triphyrins(2.1.1) exhibit more absorption in the NIR region compared to previously reported dibenzofuran-/dibenzothiophene-incorporated hybrid macrocycles. The benzofuran-incorporated triphyrin shows significant red shift in absorption bands compared to that of benzothiophene-based triphyrin due to its more coplanar arrangement as supported by X-ray and DFT studies.

Donor–acceptor type A2B2porphyrins: synthesis, energy transfer, computational and electrochemical studies

Synthesis, photophysical, electrochemical and DFT studies of donor–acceptor type A₂B₂porphyrins and their Zn(ii) and Pd(ii) complexes have been described.

Heterocyclic Nanographenes and Other Polycyclic Heteroaromatic Compounds: Synthetic Routes, Properties, and Applications

Two-dimensionally extended, polycyclic heteroaromatic molecules (heterocyclic nanographenes) are a highly versatile class of organic materials, applicable as functional chromophores and organic semiconductors. In this Review, we discuss the rich chemistry of large heteroaromatics, focusing on their synthesis, electronic properties, and applications in materials science. This Review summarizes the historical development and current state of the art in this rapidly expanding field of research, which has become one of the key exploration areas of modern heterocyclic chemistry.

Development of Ion Chemosensors Based on Porphyrin Analogues

Sensing of metal ions and anions is of great importance because of their widespread distribution in environmental systems and biological processes. Colorimetric and fluorescent chemosensors based on organic molecular species have been demonstrated to be effective for the detection of various ions and possess the significant advantages of low cost, high sensitivity, and convenient implementation. Of the available classes of organic molecules, porphyrin analogues possess inherently many advantageous features, making them suitable for the design of ion chemosensors, with the targeted sensing behavior achieved and easily modulated based on their following characteristics: (1) NH moieties properly disposed for binding of anions through cooperative hydrogen-bonding interactions; (2) multiple pyrrolic N atoms or other heteroatoms for selectively chelating metal ions; (3) variability of macrocycle size and peripheral substitution for modulation of ion selectivity and sensitivity; and (4) tunable near-infrared emission and good biocompatibility. In this Review, design strategies, sensing mechanisms, and sensing performance of ion chemosensors based on porphyrin analogues are described by use of extensive examples. Ion chemosensors based on normal porphyrins and linear oligopyrroles are also briefly described. This Review provides valuable information for researchers of related areas and thus may inspire the development of more practical and effective approaches for designing high-performance ion chemosensors based on porphyrin analogues and other relevant compounds.

Recent advances in 1,10-phenanthroline ligands for chemosensing of cations and anions

This review encompasses and highlights recent developments of 1,10-phenanthroline ligands behaving as a customized moiety used in recognition and sensing of cations and anions.

Bright, red emitting fluorescent sensor for intracellular imaging of Mg2+

A new fluorescent sensor with excellent turn-on ratio, low energy excitation and emission over 600 nm enables Mg²⁺detection in live cells.

Fluorescent and colorimetric ion probes based on conjugated oligopyrroles

In this tutorial review, the design strategies, syntheses, and ion sensing properties of conjugated oligopyrroles are described.