Multiporphyrin Arrays Research Articles

Construction of multi(iron)porphyrin array multilayers on quartz surface as peroxidase mimetics for H2O2 and glucose colorimetric, fluorometric and color-read detection

Multi(metallo)porphyrin arrays are important artificial biomimetics for mimicking the biological catalytic reactions in nature. Here, we report construction of multi(iron)porphyrin array ultrathin films on the quartz surface by coordination-driven layer-by-layer (LBL) assembling method with the Pd(II) ion as a connector and iron(III) tetrapyridylporphyrin (FeTPyP) as a linker. It is revealed that the (Pd-FeTPyP)n LBL multilayers can catalyze oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) in the presence of H2O2 with peroxidase-like activity, resulting in the formation of the blue-colored oxidized TMB (oxTMB). Coupled with glucose oxidase, three sensitive probes based on the colorimetric, fluorometric and color-read methods have been developed by using modified quartz plates as the heterogenous catalyst, with a glucose detection limit of about 0.89, 1.5 and 0.65 μM, respectively. Mechanism studies confirm an enhanced affinity between (Pd-FeTPyP)n and H2O2/TMB molecules and an improved catalytic performance, which are attributed to the reason that the FeTPyP macrocycles are well-dispersed and arranged on the two-dimensional quartz surface. Furthermore, owing to chemically anchored on the transparent quartz surface, the (Pd-FeTPyP)n films exhibit good stability with naked-eye observation of color change under moderate conditions, thus providing a potential candidate for developing colorimetric, fluorometric and color-read glucose biosensors.

Surface sensitization of graphitic carbon nitride with well-defined, organized Pd(II)-directed multiporphyrin array multilayers as ternary photocatalysts for Cr(VI) reduction in aqueous solution

Surface sensitization to a semiconductor is one of the most important strategies to increase the visible light-harvesting ability, photo-induced carrier separation and transfer rate, thus improving the photocatalytic efficiency. Here, ternary nanocomposites are constructed by a Pd(II)-directed layer-by-layer (LBL) coordination bonding of tetrakis(4-aminophenyl)porphyrin (TAPP) on the oxidized graphitic carbon nitride (O-g-C3N4). The nanocomposites of O-g-C3N4@(Pd-TAPP)n as-produced present a porous and ultra-thin lamellar structure with an enhanced absorption ability in the visible light region. As the heterogeneous photocatalyst, O-g-C3N4@(Pd-TAPP)n can reduce the toxic hexavalent Cr(VI) species under visible light irradiation with no need for the sacrificial agent. Further, the photocatalytic activity is enhanced by orders of magnitude higher than that before the surface modification, attributed to the reasons of increased specific surface area, elevated light utilization, meliorative charge separation and transfer rate, as well as the synergistic effect by the multiporphyrin arrays and coordinated Pd(II)/(0) species. In addition to the features of without need of sacrificial agent and irradiation under visible light, the Pd-TAPP multilayer modified nanocomposites have well stability and reusability, resulting in a possibility for the practical application.

Multiporphyrinic architectures: Advances in structural design for photodynamic therapy

AbstractRationally designed multiporphyrinic architectures for boosting photodynamic therapy (PDT) have attracted significant attentions recently years due to their great potential for light‐mediated generation of reactive oxygen species. However, there is still a gap between the structure design and their PDT performance for biomedical applications. This tutorial review provides a historical overview on (i) the basic concept of PDT for deeply understanding the porphyrin‐mediated PDT reactions, (ii) developing strategies for constructing porphyrinic architectures, like nanorings, boxes, metal‐organic frameworks (MOFs), covalent‐organic frameworks (COFs), vesicles, etc., where we classified into the following three categories: multiporphyrin arrays, porphyrinic frameworks, and others porphyrin assemblies, (iii) the various application scenarios for clinical cancer therapy and antibacterial infection. Also, the existing challenges and future perspectives on the innovation of porphyrinic architectures for clinical PDT applications are mentioned in the end section. Moreover, the porphyrinic nanomaterials with atomically precise architectures provide an ideal platform for investigating the relationship between structures and PDT outputs, design of personalized “all‐in‐one” theranostic agents, and the popularization and application in wider biomedical fields.

Post-synthetic DNA modification with porphyrins for DNA-templated supramolecular assemblies

The use of azide-alkyne cycloaddition (“click chemistry”), both Cu-catalysed and Cu-free, was probed to attach different porphyrins onto oligodeoxynucleotides (ODNs), and the efficiency was compared to amide coupling reaction. Terminal attachment using the different methodologies provides porphyrin-ODNs in varying yields, and the porphyrin-ODNs can be transformed into multiporphyrin arrays using DNA-templated assembly. These arrays show exciton coupling between the porphyrin units and thus demonstrate an efficient and alternative route to multiporphyrin assemblies.

Synthesis and functionalization of electron-deficient perfluoroalkyl porphyrin building blocks for supermolecular systems

Synthetic strategies for electron-deficient meso-perfluoroalkylporphyrins bearing diverse functional groups are described. Scalable and efficient syntheses for 5-triisopropylsilylethynyl-10,15,20-tris(heptafluoropropyl)porphyrin and 5-triisopropylsilylethynyl-10,20-bis(heptafluoropropyl)porphyrin that equip meso-ethynyl functional groups via the bilane route have been established, along with a refined route to [5,15-bis(heptafluoropropyl)porphinato]zinc(II). meso-Position halogenation of [5,15-bis(heptafluoropropyl)porphinato]zinc(II) was achieved by selective meso-nitration and subsequent reduction, diazonium salt formation, and iodination reactions. Computational data describe the low energy excited states of these chromophores and the electronic structural factors that control reactivity of these meso-perfluoroalkyl substituted porphyrin complexes. meso-Functionalized [5-triisopropylsilylethynyl-10,20-bis(heptafluoropropyl)porphinato]zinc(II) and [5-iodo-10,20-bis(heptafluoropropyl)porphinato]zinc(II) building blocks lay the foundation for the construction of highly conjugated multiporphyrin arrays that feature electronic structural properties important for the development of n-type materials and high potential photooxidants.

Bioinspired Applications of Porphyrin Derivatives.

Porphyrin derivatives are ubiquitous in nature and have important biological roles, such as in light harvesting, oxygen transport, and catalysis. Owing to their intrinsic π-conjugated structure, porphyrin derivatives exhibit characteristic photophysical and electrochemical properties. In biological systems, porphyrin derivatives are associated with various protein molecules through noncovalent interactions. For example, hemoglobin, which is responsible for oxygen transport in most vertebrates, consists of four subunits of a globular protein with an iron porphyrin derivative prosthetic group. Furthermore, noncovalently arranged porphyrin derivatives are the fundamental chromophores in light-harvesting systems for photosynthesis in plants and algae. These biologically important roles originate from the functional versatility of porphyrin derivatives. Specifically, porphyrins are excellent host compounds, forming coordination complexes with various metal ions that adds functionality to the porphyrin unit, such as redox activity and additional ligand binding at the central metal ion. In addition, porphyrins are useful building blocks for functional supramolecular assemblies because of their flat and symmetrical molecular architectures, and their excellent photophysical properties are typically utilized for the fabrication of bioactive functional materials. In this Account, we summarize our endeavors over the past decade to develop functional materials based on porphyrin derivatives using bioinspired approaches. In the first section, we discuss several synthetic receptors that act as artificial allosteric host systems and can be used for the selective detection of various chemicals, such as cyanide, chloride, and amino acids. In the second section, we introduce multiporphyrin arrays as mimics of natural light-harvesting complexes. The active control of energy transfer processes by additional guest binding and the fabrication of organic photovoltaic devices using porphyrin derivatives are also introduced. In the third section, we introduce several types of porphyrin-based supramolecular assemblies. Through noncovalent interactions such as metal-ligand interaction, hydrogen bonding, and π-π interaction, porphyrin derivatives were constructed as supramolecular polymers with formation of fiber or toroidal assembly. In the last section, the application of porphyrin derivatives for biomedical nanodevice fabrication is introduced. Even though porphyrins were good candidates as photosensitizers for photodynamic therapy, they have limitations for biomedical application owing to aggregation in aqueous media. We suggested ionic dendrimer porphyrins and they showed excellent photodynamic therapy (PDT) efficacy.

Rapid Exciton Migration and Amplified Funneling Effects of Multi-Porphyrin Arrays in a Re(I)/Porphyrinic MOF Hybrid for Photocatalytic CO2 Reduction.

A porphyrinic metal-organic framework (PMOF) known as PCN-222(Zn) was chemically doped with a molecular Re(I) catalyst-bearing carboxylate anchoring group to form a new type of metal-organic framework (MOF)-Re(I) hybrid photocatalyst. The porphyrinic MOF-sensitized hybrid (PMOF/Re) was prepared with an archetypical CO2 reduction catalyst, (L)ReI(CO)3Cl (Re(I); L = 4,4'-dicarboxylic-2,2'-bipyridine), in the presence of 3 vol % water produced CO with no leveling-off tendency for 59 h to give a turnover number of ≥1893 [1070 ± 80 μmol h-1 (g MOF)-1]. The high catalytic activity arises mainly from efficient exciton migration and funneling from photoexcited porphyrin linkers to the peripheral Re(I) catalytic sites, which is in accordance with the observed fast exciton (energy) migration (≈1 ps) in highly ordered porphyrin photoreceptors and the effective funneling into Re(I) catalytic centers in the Re(I)-doped PMOF sample. Enhanced catalytic performance is convincingly supported by serial photophysical measurements including decisive Stern-Volmer interpretation.

Interfacial self-assembly of manganese multiporphyrin arrays on multi-walled carbon nanotubes as heterogeneous catalysts for degradation of toxic naphthols in aqueous solution

Artificial pigments of metalloporphyrin derivatives are effective catalysts for the degradation of toxic organic dyes, phenols, and other pollutants. We reported here an interfacial layer-by-layer (LBL) assembly of multiporphyrin arrays on the surface of multi-walled carbon nanotubes (MWNTs) with the use of Na2PdCl4 as a connector and manganese (III) meso-tetra(4-pyridyl)porphine acetate (MnTPyP) as a linker, respectively. Thermogravimetric analysis revealed that the relative content of organic species in the MWNT@(Pd-MnTPyP)n nanocomposites increased gradually with more layers of Pd-MnTPyP assembled. The Soret absorption band of MnTPyP displayed approximately 20-nm redshift in the nanocomposites due to the increase of porphyrin-porphyrin interaction within the Pd-MnTPyP ultrathin films. The specific surface area was about 513.1 and 47.7 m2/g for the original MWNTs and MWNT@(Pd-MnTPyP)3 nanocomposites, respectively. Finally, the nanocomposites were used as heterogeneous catalysts for catalytic degradation of toxic 1-naphthol, 1,5-dihydroxynaphthalene, 5-amino-1-naphthol, and 1-naphthol-5-sulphonic acid in phosphate buffer, using H2O2 as the oxidant. It was revealed that, when the nanocomposites were used, the catalytic efficiency could increase by 2 to 3 orders of magnitude. Higher catalytic efficiency was observed for the naphthols bearing the electron-donating group of hydroxyl or amino than those bearing an electron-withdrawing group of sulfonic acid.

Interfacial self-assembly of nanoZnO@multiporphyrin array hybrids as binary light-sensitizers for photocurrent generation and photocatalytic degradation of organic pollutants

Both porphyrins and nanoscale ZnO semiconductors (nanoZnO) are important eco-friendly light-sensitizers and photocatalysts in academic researches and industrial applications. Here, ultrathin films of multiporphyrin arrays were constructed on the surface of nanoZnO to produce binary hybrids based on the coordination reaction of Pd(II) ions and tetrapyridylporphyrin (TPyP). The hybrids of nanoZnO@(Pd–TPyP)n as-produced displayed an improved absorption ability from 200 to 700 nm and an effective energy transfer between the multiporphyrin arrays and nanoZnO cores. Benefit from such a synergistic effect, their photocatalytic performance was largely improved as compared with that of the original porphyrins and nanoZnO particles. Particularly, under only visible light radiation, the photocurrent density of nanoZnO@(Pd–TPyP)n hybrids was approximately 25 times stronger and the photocatalytic efficiency on the degradation of Rhodamine B was over 10 times higher as compared with that of the original nanoZnO particles. Finally, because the multiporphyrin arrays were anchored on the nanoZnO’s surfaces via the covalent and coordinative bonding, the present nano-hybrids displayed not only structural controllability at the molecular level but also well stability, reusability, and recyclability as the heterogeneous photocatalysts.

Bridging and Conformational Control of Porphyrin Units through Non-Traditional Rigid Scaffolds.

Connecting two porphyrin units in a rigid linear fashion, without any undesired electron delocalization or communication between the chromophores, remains a synthetic challenge. Herein, a broad library of functionally diverse multi‐porphyrin arrays that incorporate the non‐traditional rigid linker groups cubane and bicyclo[1.1.1]pentane (BCP) is described. A robust, reliable, and versatile synthetic procedure was employed to access porphyrin‐cubane/BCP‐porphyrin arrays, representing the largest non‐polymeric structures available for cubane/BCP derivatives. These reactions demonstrate considerable substrate scope, from utilization of small phenyl moieties to large porphyrin rings, with varying lengths and different angles. To control conformational flexibility, amide bonds were introduced between the bridgehead carbon of BCP/cubane and the porphyrin rings. Through varying the orientation of the substituents around the amide bond of cubane/BCP, different intermolecular interactions were identified through single crystal X‐ray analysis. These studies revealed non‐covalent interactions that are the first‐of‐their‐kind including a unique iodine‐oxygen interaction between cubane units. These supramolecular architectures indicate the possibility to mimic a protein structure due to the sp3 rigid scaffolds (BCP or cubane) that exhibit the essential conformational space for protein function while simultaneously providing amide bonds for molecular recognition.

Sn(IV) Multiporphyrin Arrays as Tunable Photoactive Systems.

A series of four arrays made of a central Sn(IV) porphyrin as scaffold axially connected, via carboxylate functions, to two free-base porphyrins has been prepared and fully characterized. Three arrays in the series feature the same free-base unit and alternative tin-porphyrin macrocycles, and one consists of a second type of free-base and one chosen metallo-porphyrin. A thorough photophysical investigation has been performed on all arrays by means of time-resolved emission and absorption techniques. Specific focus has been given at identifying how structural modifications of the free-base and tin-porphyrin partners and/or variation of the solvent polarity can effectively translate into distinct photophysical behaviors. In particular, for systems SnTPP(Fb)2 (1) and SnOEP(Fb)2 (2), an ultrafast energy transfer process from the excited Sn(IV) porphyrin to the free-base unit occurs with unitary efficiency. For derivative SnTPP(FbR)2 (3), the change of solvent from dichloromethane to toluene is accompanied by a neat change in the intercomponent quenching mechanism, from photoinduced electron transfer to energy transfer, upon excitation of the Sn(IV) porphyrin unit. Finally, for array SnTpFP(Fb)2 (4), an ultrafast electron transfer quenching of both chromophores is detected in all solvents. This work provides a general outline, accompanied by clear experimental support, on possible ways to achieve a systematic fine-tuning of the quenching mechanism (from energy to electron transfer) of Sn(IV) multiporphyrin arrays.

Fabrication of multiporphyrin@g-C3N4 nanocomposites via Pd(II)-directed layer-by-layer assembly for enhanced visible-light photocatalytic activity

Graphitic carbon nitride and its nanocomposites with other functional species are attractive light-sensitizers, especially for the development of new opto-electrical devices and photocatalysts in terms of persistant organic pollutants degradation. Herein, oxidized g-C3N4 (O-C3N4) rich in hydroxyl and carboxyl functional groups, was selected as a support to bind with multiporphyrin arrays via a layer-by-layer assembling process, using PdCl42− as connectors and 5,10,15,20-tetra(4-pyridyl)-21H,23H-porphine (TPyP) as linkers. The as-obtained multiporphyrin@g-C3N4 nanocomposites exhibited dramatic photocatalytic visible-light degradation of Rhodamine B and phenol. The experimental results demonstrated that TPyP was not just as the photosensitizer, but also a charge promotor to retard the recombination of the excited electrons and holes of g-C3N4. Both the holes and O2− are main oxidative species of multiporphyrin@g-C3N4 nanocomposites for photodegradation under visible light irradiation. Finally, the possible charge transfer mechanism of enhanced photocatalytic activity was proposed.

Assembly and X-ray crystal structures of heterometallic multiporphyrins with complementary coordination between ruthenium(II) and tin(IV) porphyrins

Two new heterometallic multiporphyrins Sn-Ru4 and Sn-Ru6 have been synthesized by adopting two simple approaches based on metal ion recognition by a ditopic ligand and mutually non-interfering coordination properties of the Ru(II)-N and Sn(IV)-O interactions. We have synthesized the pentameric Sn-Ru4 and the heptameric Sn-Ru6 using trans-dihydroxo[5,10,15,20-tetrakis(4-pyridyl)porphyrinato]tin(IV) and trans-diisonicotinato[5,10,15,20-tetrakis(4-pyridyl)porphyrinato]tin(IV), respectively, from the reaction with [5,10,15,20-tetrakis(4-tert-butylphenyl)porphyrinato]ruthenium(II)carbonyl [(TtBPP)Ru(CO)]. The reaction of Sn-Ru4 with 2 equivalents of isonicotinic acid followed by 2 equivalents of [(TtBPP)Ru(CO)] in refluxing CHCl3 also leads the formation of Sn-Ru6. The formation of newly hybrid multiporphyrin arrays were confirmed by 1H NMR spectroscopic studies and single crystal X-ray diffraction techniques. 1H NMR measurements on Sn-Ru4 and Sn-Ru6 indicate that the protons on the core template are extremely shielded as a result of the anisotropy of the peripheral porphyrin units. X-ray crystallographic analysis reveals an open-box shaped pentaporphyrin array for Sn-Ru4 and the full encapsulation of a Sn(IV) porphyrin moiety surrounded by six Ru(II) porphyrin units in Sn-Ru6. So far no example of well-defined X-ray crystallographic structure for Sn(IV) porphyrins with high nuclearity is reported.

Fabrication of carbon nanotube-multiporphyrin array composites as light-sensitizer for photocurrent generation, photochromism of viologen and catalytic degradation of methyl orange

Multiporphyrin arrays were assembled on the surface of MWNTs to produce light-sensitive nano-composites with improved opto-electric conversion efficiency, photochromic, and photocatalytic performance.

Non-Covalently Linked Multiporphyrin Arrays by Metal Coordination

Non-Covalently Linked Multiporphyrin Arrays by Metal Coordination

Palladium-directed self-assembly of multi-titanium(IV)-porphyrin arrays on the substrate surface as sensitive ultrathin films for hydrogen peroxide sensing, photocurrent generation, and photochromism of viologen

Multiporphyrin arrays are large, π-conjugated chromophores with high absorption efficiency and strong chemical stability that play an important role in supramolecular and advanced material sciences. Palladium-directed self-assembly of multiporphyrin array ultrathin films was achieved on substrate surfaces using oxo[5,10,15,20-tetra(4-pyridyl)porphyrinato]titanium (IV) complex [TiO(TPyP)] as a linker and sodium tetrachloropalladate (Na2PdCl4) as a connector. The Pd-TiOTPyP films as prepared were characterized by using UV–vis absorption and X-ray photoelectron spectroscopy, as well as by atomic force and scanning electron microscopy. The Soret absorption band of TiOTPyP was observed to red shift by 6nm when the Pd-TiOTPyP multilayer-modified quartz substrate was immersed in an aqueous solution containing hydrogen peroxide. This was attributed to the formation of a TiO2TPyP monoperoxo complex. This oxidation reaction could be accelerated in an acidic solution. Furthermore, the immobilized Pd-TiOTPyP multilayers could act as light-harvesting units for photocurrent generation and photochromism of viologens, with strong stability, reproducibility, and recyclability. The photocurrent density could be enhanced in electrolyte solutions containing electron donors such as triethanolamine, or electron acceptors such as viologens. Finally, photoinduced reduction (photochromism) of viologens was investigated using the Pd-TiOTPyP multilayers as light sensitizers and EDTA as the electron donors.

Design and Synthesis of Porphyrin Oligomers and Porphyrinoids Via Suzuki-Miyaura Reaction

In view of multi-porphyrin arrays and new porphyrinoids, whih has potential applications in optoelectronic devices, sensors, photovoltaic devices, non-linear optical(NLO) materials, photodynamic therapy (PDT) pigments, light-harvesting models, and host-guest chemistry. Both the manipulation of interporphyrinic interaction and design of new structural porphyrinods are often essential to achieve desirable electronic and photophysical properties. Recently, the Osuka group developed a transition metal-catalyzed coupling reaction that has been proven to be very useful to construct multiporphyrinic systems. Till now we have adopted this strategy and prepared many heterocycles bridged β-to-β porphyrin arrays, including direct-bridged β-to-β porphyrin nanorings[ 1 ], earring porphyrins[ 3 ]. The experiment results indicated that the building blocks will remarkably affect the target molecules. As the bridge is thienylene, the main products is cyclic dimer, trimer, when the bridge is pyridylene, there are trace cyclic products are obtained. when the bridge is free base or Zn(II) porphyrin, bigger loop are formed, while Ni(II)porphyrin is used, the products is much simple. As to synthesis of porphyrin nanobarrel, if the porphyrin monomer is free base or Zn(II) porphyrin, no porphyrin barrel is obtained, which means that only ruffled Ni(II)porphyrin monomers can be used to synthesis porphyrin barrels. Synthesis of direct linked porphyrin nanorings is affected by the meso-substituent on porphyrin, when the substituent is aryl, only trimer and twinned pentamer can be prepared, when the substituent is alkyl, tetramer and twinned heptamer can be obtained.The photophysical study revealed that these porphyrin arrays and porphyrinoids exhibit either longer fluorescent lifetime, larger two photon absorption values or Near-infrared absorptions. Some new porphyrin arrays or porphyrinnoids recently have been constructed through Pd-catalyzed cross-coupling reactions (Figure 1), further study on their properties is underway in our lab. Figure 1. Crystals of earring porphyrins and multi-porphyrin arrays

Meso-Linked Multiporphyrins as Model for Light Harvesting Systems: Review

Nature has always been the fundamental source of inspiration for researchers to understand the complex biological functions. Photosynthesis is among the important natural phenomena and hence, gained interest towards developing the artificial photosynthetic reaction centers. Electron and energy transfer process between various porphyrin units within the multiporphyrin arrays is the important key in developing such systems. Long duration of charge separated state and spectral coverage scope of the accepting porphyrin units are another important factor that contribute to an efficient mimic of the photosynthetic reaction center. Meso-linked porphyrin architectures provide a great aspect in this regard because of short inter-porphyrinic distance with optimal dihedral angle. The present review highlights the design of various kinds of meso-linked multiporphyrins and study of electron and energy transfer processes between them that serve as an efficient model for light harvesting systems.

Guest-Induced Modulation of the Energy Transfer Process in Porphyrin-Based Artificial Light Harvesting Dendrimers.

A series of dendritic multiporphyrin arrays (PZnTz-nPFB; n = 2, 4, 8) comprising a triazole-bearing focal zinc porphyrin (PZn) with a different number of freebase porphyrin (PFB) wings has been synthesized, and their photoinduced energy transfer process has been evaluated. UV/vis absorption, emission, and time-resolved fluorescence measurements indicated that efficient excitation energy transfer takes place from the focal PZn to PFB wings in PZnTz-nPFB's. The triazole-bearing PZn effectively formed host-guest complexes with anionic species by means of axial coordination with the aid of multiple C-H hydrogen bonds. By addition of various anionic guests to PZnTz and PZnTz-nPFB's, strong bathochromic shifts of PZn absorption were observed, indicating the HOMO-LUMO gap (ΔEHOMO-LUMO) of PZn decreased by anion binding. Time-resolved fluorescence measurements revealed that the fluorescence emission predominantly takes place from PZn in PZnTz-nPFB's after the addition of CN-. This change was reversible because a treatment with a silver strip to remove CN- fully recovered the original energy transfer process from the focal PZn to PFB wings.

Heteroatom-Containing Porphyrin Analogues.

The heteroatom-containing porphyrin analogues or core-modified porphyrins that resulted from the replacement of one or two pyrrole rings with other five-membered heterocycles such as furan, thiophene, selenophene, tellurophene, indene, phosphole, and silole are highly promising macrocycles and exhibit quite different physicochemical properties compared to regular azaporphyrins. The properties of heteroporphyrins depend on the nature and number of different heterocycle(s) present in place of pyrrole ring(s). The heteroporphyrins provide unique and unprecedented coordination environments for metals. Unlike regular porphyrins, the monoheteroporphyrins are known to stabilize metals in unusual oxidation states such as Cu and Ni in +1 oxidation states. The diheteroporphyrins, which are neutral macrocycles without ionizable protons, also showed interesting coordination chemistry. Thus, significant progress has been made in last few decades on core-modified porphyrins in terms of their synthesis, their use in building multiporphyrin arrays for light-harvesting applications, their use as ligands to form interesting metal complexes, and also their use for several other studies. The synthetic methods available in the literature allow one to prepare mono- and diheteroporphyrins and their functionalized derivatives, which were used extensively to prepare several covalent and noncovalent heteroporphyrin-based multiporphyrin arrays. The methods are also developed to synthesize different hetero analogues of porphyrin derivatives such as heterocorroles, heterochlorins, heterocarbaporphyrinoids, heteroatom-substituted confused porphyrins, and so on. This Review summarizes the key developments that have occurred in heteroporphyrin chemistry over the last four decades.