Potential Nonlinear Optical Material Research Articles

The third-order nonlinear optical responses of zinc porphyrin oligomers: Cycles vs linear chains

Porphyrins are widely used as potential nonlinear optical (NLO) materials because of their highly delocalized π electrons and feasible synthesis and functionalization with broad biological applications. A variety of linear and cyclic porphyrin derivatives have been synthesized, and the correlation between their structures and NLO properties awaits being disclosed. In this work, the electronic structures and third-order NLO properties of linear and cyclic butadiyne-linked zinc porphyrin oligomers have been studied by quantum chemical methods and sum-over-states model. The static second hyperpolarizability (<γ0>) increases exponentially with the number of zinc porphyrin units ([<γ0>n] = 0.67[<γ0>1]n2.63, n = 2 ∼ 6) in linear π-conjugated oligomers, and the <γ0> of the linear hexamer is about 74 times that of the monomer. Such enhancement of <γ0> in linear oligomers originates from closely-lying frontier molecular orbitals available for low energy electron excitations and strong charge transfer-based excitations across porphyrins. The <γ0>s of cyclic porphyrins are lower than that of the linear hexamer, though the interaction between the ring and the ligand enhances the <γ0> of some cyclic zinc porphyrin complexes. The large two-photon absorption cross sections confer on these zinc porphyrin derivatives excellent candidates for two-photon absorption applications.

A first principles based prediction of electronic and nonlinear optical properties towards cyclopenta thiophene chromophores with benzothiophene acceptor moieties

In the current work, organic cyclopenta-thiophene (CPT) based derivatives (FICR and FICD1–FICD5) were designed by the modulation of end-capped acceptor group of the reference molecule i.e., FICR, to explore their nonlinear optical (NLO) response. The effect of terminal acceptor and donor groups in the tailored compounds was explored by using DFT based quantum calculations. The UV–Vis analysis, frontier molecular orbitals (FMOs), transition density matrix (TDM), natural bond orbitals (NBOs), density of states (DOS), nonlinear optical (NLO) analyses were performed at M06/6-311G(d,p) functional. The LUMO–HOMO band gaps of FICD1–FICD5 were found to be smaller (1.75–1.92 eV) comparative to FICR (1.98 eV). Moreover, the global reactivity parameters (GRPs) were correlated with the results of other analyses. FICD2 and FICD5 with lowest band gap 1.73 and 1.75 eV showed less hardness (0.86 and 0.87 eV, respectively), high softness (0.58 and 0.57 eV−1), and larger absorption spectrum (815 and 813 nm) in gaseous phase and (889 and 880 nm) in solvent phase among all entitled compounds. All the designed chromophores (FICD1–FICD5) demonstrated a significant NLO response as compared to FICR. Particularly, FICD2 and FICD5 exhibited the highest average linear polarizability (<α>) [2.86 × 10−22 and 2.88 × 10−22 esu], first hyperpolarizability (βtot) (8.43 × 10−27 and 8.35 × 10−27 esu) and second hyperpolarizability (γtot) (13.20 × 10−32 and 13.0 × 10−32 esu) values as compared to the other derivatives. In nutshell, structural modeling of CPT based chromophores with extended acceptors, can be significantly utilized to achieve potential NLO materials.

Theoretical investigation of the electronic and second-order non-linear optical properties of [n]helicene derivatives

Designing and synthesizing nonlinear optical materials with excellent performance has always been a persistent goal pursued by material chemists. In paper, based on the reported [6]heliceno-bis(naphthalimides) 2, four new molecules are designed by introducing 2-dicyanomethylene-1,3-dithiole on the two middle benzene rings of the naphthalimide unit and replacing CH3 units on the R1 and R2 substituents with NH2/NO2 moieties, or their combination. The electronic spectra, reorganization energy and second-order nonlinear optical properties of the reported derivatives 1 and 2, as well as four newly designed derivatives, have been systematically investigated by means of (time-dependent) density functional theory calculations. Frontier molecular orbital analysis, electron excitation analysis, reorganization energy, and the calculation of the static and dynamic first hyperpolarizability all indicate that the studied system is greatly influenced by the number of benzene rings in helicene core and the terminal substituents attached at both ends of helicene core. Further analysis of depolarization, hyperpolarizability density and unit sphere representation reveals the nature of the nonlinear optical response of the studied system. Considering that the studied derivatives all have large static first hyperpolarizabilities (e.g., 210 × 10-30 esu for derivative 5) and small reorganization energy (e.g., 0.092 eV of hole reorganization energy and 0.118 eV of electron reorganization energy for derivative 3), they are expected to become potential nonlinear optical materials with excellent performance and bipolar transport materials. This work contributes to the rational design of high-performance molecules based on [n]helicenes derivatives and further explores their potential applications in optical materials.

Strong Second-Harmonic Generation Induced by a Triphenylamine-Based Bismuth-Organic Framework for Photocatalytic Activity Enhancement.

Taking advantage of the well-defined geometry of metal centers and highly directional metal-ligand coordination bonds, metal-organic frameworks (MOFs) have emerged as promising candidates for nonlinear optical (NLO) materials. In this work, taking a photoresponsive carboxylate triphenylamine derivative as an organic ligand, a bismuth-based MOF, Bi-NBC, NBC = 4',4‴,4‴″-nitrilotris(([1,1'-biphenyl]-4-carboxylic acid)) is obtained. Structure determination reveals that it is a potential NLO material derived from its noncentrosymmetric structure, which is finally confirmed by its rarely strong second harmonic generation (SHG) effect. Theoretical calculations reveal that the potential difference around Bi atoms is large; therefore, it leads to a strong local built-in electric field, which greatly facilitates the charge separation and transfer and finally improves the photocatalytic performance. Our results provide a reference for the exploration of MOFs with NLO properties.

Centrosymmetric CaBaMF8 and Noncentrosymmetric Li2CaMF8 (M = Zr, Hf): Dimension Variation and Nonlinear Optical Activity Resulting from an Isovalent Cation Substitution-Oriented Design.

Zirconium/hafnium fluorides have recently been recognized as potential nonlinear optical (NLO) materials with short ultraviolet (UV) cutoff edges, which is significant in laser science and industry. The synthesis of noncentrosymmetric (NCS) materials based on centrosymmetric (CS) compounds by an isovalent cation substitution-oriented design is an emerging strategy in the NLO territory. Here, two isostructural and novel fluorides, CaBaMF8 (M = Zr (1), Hf (2)), have been synthesized through the combination of alkaline earth metals, zirconium/hafnium, and fluorine elements. They feature zero-dimensional and CS structures composed by an isolated MF8 (M = Zr, Hf) dodecahedron and dissociative Ca2+ and Ba2+ cations, and they display short UV cutoff edges (<200 nm) as well. Two three-dimensional fluorides Li2CaMF8 (M = Zr (3), Hf (4)) are obtained by replacing Ba with alkali metal Li atom, which not only represent phase-matchable second-harmonic-generation activities (0.36, 0.30× KH2PO4 (KDP)) at 1064 nm but also maintain short UV cutoff edges with high reflectance. This work has largely enriched the family of NCS zirconium/hafnium fluorides reaching the short UV region.

Monolithic PMN-39PT nanograting-assisted second harmonic generation enhancement.

Second harmonic generation plays a vital role in frequency conversion which mutually promotes the laser technology and allows the wavebands extension of new coherent source. The monolithic crystals are supposed to be a superior choice for harmonic generation due to long interaction distance, however, the phase-mismatch brought a sharp reduction in the conversion efficiency. Although birefringent phase-matching and quasi-phase-matching techniques are commonly utilized to fill the phase gap in monolithic crystals, these techniques are limited by the natural refractive index of crystal and the domain engineering, respectively. In recent years, subwavelength structures evolve as a flexible scheme to realize phase matching by engineering the geometry features of crystals. Here, structured nanogratings are designed and fabricated on a monolithic PMN-39PT (Pb(Mg1/3Nb2/3)O3-0.39PbTiO3) substrate, a novel ferroelectric crystal with promising optical prospect, for enhancing second harmonic generation, where birefringent or quasi phase-matching is hard to achieve. The nanograting-assisted second harmonic generation enhancement is observed which is not limited by the availability of thin crystalline films. Meanwhile, a boost in the second harmonic signal synchronously promotes the cascading third harmonic generation. This method may provide an alternative solution for enhanced harmonic generation on monolithic substrates and develop potential nonlinear optical materials for frequency conversion.

Rational Design of Novel Promising Infrared Nonlinear Optical Materials: Structural Chemistry and Balanced Performances.

ConspectusSecond-order nonlinear optical (NLO) materials are currently a hot topic in modern solid-state chemistry and optics because they can produce coherent light by frequency conversion. Noncentrosymmetric (NCS) structure is not only the prerequisite for NLO materials but also a challengeable issue because materials tend to be centrosymmetric (CS) in terms of thermodynamical stability. Among NLO materials, an excellent infrared (IR) candidate should simultaneously meet several strict key conditions including a large NLO coefficient, high laser-induced damage threshold (LIDT), phase-matchable (PM) behavior, and so on. Achieving a balance between the large NLO effect and high LIDT is difficult, as they have contradictory requirements for chemical bonds. Considering the urgent need of the high-power IR laser market and the drawbacks of the available ones, exploring new high-performance IR NLO crystals is necessary while challenging. In this Account, we first briefly introduce the status and advancement of IR NLO crystals and emphasize the criteria of an excellent candidate. Then, we will introduce five simple methods developed by us to discover practical NLO candidates through understanding of the chemical composition-structure-NLO performance relationship. (1) A rarely investigated system with simple chemical compositions as new-type NLO crystals, namely, adducts containing S8 molecules, are developed. Combining a chairlike S8 unit with other units through van der Waals forces has successfully obtained several high-performance NLO adducts. (2) The main trend in exploring new NLO crystals is that the chemical composition is more and more diversified and the structure is more and more complex, and expensive and chemically active alkaline and alkaline earth metals are usually introduced as counter cations. In contrast, the research on systems with simple chemical compositions, simple structures, and low costs has been continuously ignored. The binary M2Q3 (M = Ga, In; Q = S, Se) family with rich acentric modifications has been systematically investigated, and they all exhibit strong SHG effects and high LIDTs. (3) We first proposed the concept of inducing CS structures transformed to NCS ones by partial cation substitution to design novel NLO crystals. Considering the huge number of CS structures in the database compared to the number of NCS structures, it is an attractive method to apply CS structures as the parents to obtain potential NLO materials via partial-substitution-induced symmetry breaking. A series of chalcogenides with high NLO performances have been successfully obtained by us in this way. (4) We investigated the first NLO-active rare earth (RE) chalcophosphates and developed this family systematically, and they demonstrate wonderful comprehensive NLO properties. (5) We created a novel mixed-anion system for NLO applications, namely, chalcogenide borates. Usually, mixed-anion compounds can engender a synergistic effect to obtain desired IR NLO properties. Our recent progress on this system suggests that chalcogenide borates are potential candidates for IR NLO applications, although the study is still in its infancy. Finally, we state the current problems of IR NLO materials and give some perspectives for their future development.

Crystal Growth and Characterisation of Strontium on Thiourea

Thiourea, being a potential organic Non-linear optical material with high SHG efficiency having application in laser technology and photonic applications are grown as single crystals of Strontium chloride doped thioureaby slow evaporation solution growth technique (SEST), one of the best method for crystal growth at room temperature. It is furtheranalysed by single crystal XRD which infers thatthe Strontium Chloride doped thiourea crystal has monoclinicsystem. The surface morphology was studied by SEM-EDS, that confirms thepresence of Strontium in the doped specimen. FTIR reveals some slight variation in vibrational frequencies and no secondaryvibrational bandsarefoundin the doped specimen indicating the presence of some dopant

A potential nonlinear optical material for crown-porphyrin complexes: Alkali metal doping and transition metal introducing

Crown ethers have inspired the rapid growth of research interest in the design and synthesis of functional materials due to their exceptional affinity for metal. In this work, a fascinating crown-porphyrin (Cr-Pr) complexes were studied with doping alkali metal (potassium, K atom) on the crown ether face and introducing transition metal (zinc, Zn atom) on the porphyrin face. The research reveals that the Cr-Pr complex with doped K and Zn atoms results in significant variations in nonlinear optical (NLO) properties. Interestingly, the crown ether ring with the K atom in the K@Cr-Pr complex leads to a remarkable first hyperpolarizability (βtot). On the contrary, when introducing the Zn atom in porphyrins, the Cr-Pr@Zn complex exhibits no significant change in NLO response. Further, the combination of the K and Zn atoms in crown-porphyrin complex (K@Cr-Pr@Zn) can result in significant enhancement of their NLO characteristics, which is much greater than that of the K@Cr-Pr and the Cr-Pr@Zn complexes. The natural population analysis (NPA) and the molecular electrostatic potential maps (ESP) show that the doping of the K atom regulates effectively charge distribution in the complexes. Moreover, the great βtot value can be further illustrated by their low transition energies and an obvious charge transfer (CT) transition in the main excited states. Therefore, the current work achieves that the NLO properties of crown ether derivatives can be regulated by doping alkali metals in the crown ether ring and provides a theoretical guide for developing high-performance NLO devices.

Tuning nonlinear optical properties of tetracyclopentatetraphenylnene by superhalogens doping: Quantum chemical perspective of novel NLO materials for modern optoelectronic applications

Fabrication of stable NLO materials is highly demanding because of their numerous applications in optoelectronic and optical devices. This research attempts to theoretically design superhalogens (LiF2, BeF3, MgF3, LiCl2, BeCl3, MgCl3) doped tetracyclopentatetraphenylnene (TCPTP) as potential NLO materials for cutting-edge NLO applications. Density functional theory (DFT) computations explore their geometric, thermodynamic, electrical, and nonlinear optical (NLO) properties. NCI analysis, DOS, FMO, MEP, TDM, and NBO analysis are performed to confirm the type of interaction, participation of various fragments, and charge transfer, respectively. The computational findings demonstratedthat the superhalogen-doped isomers of TCPTP have remarkablethermodynamic stabilities, with the highestbinding energy of −81.344 kcalmol−1. The HOMO–LUMO energy gap was significantly decreased from 1.5319 eV (TCPTP) to 1.2807––1.2269 eV by superhalogens doping. The TD-DFT analysis demonstrates that these proposed complexes have sufficient transparency in the UV region, which is necessary to add a high nonlinear optical response for valuable applications in optoelectronics. Magnification in the dipole moment (µ0), polarizability (α0), and hyperpolarizability (β0) values from 0.0 D, 325.00 a.u. and 0.0 a.u to 18.23 D, 463.92 a.u and 4.11 × 104 a.u respectively, is achieved upon superhalogens doping on TCPTP surface. These complexes also had considerably large initial hyperpolarizability (βo) from 1.57 × 103 to 4.11 × 104 au, which was particularly noteworthy. This research with promising initial hyperpolarizability (βo) value will provide new opportunities for experimental and theoretical researchers to develop innovative NLO materials.

Diamondoid as potential nonlinear optical material by superalkali doping: A first principles study

Adamantane (C10H16), the smallest diamondoid molecule, has sparked considerable scientific interest due to its symmetric, single cage-shaped structure. In the current work, the geometric, electronic, and nonlinear optical responses of Li3O, Na3O and K3O clusters doped adamantanes have been investigated via DFT simulations. The calculated values of interaction energies (−5.50 to −6.91 kcal/mol) and vertical ionization energies (3.01–3.56 eV) reflected that the designed M3O-Ada complexes are thermodynamically and chemically stable. Charge transfer is probed through natural population analysis and the highest charge transfer (0.038 |e|) is observed for K3O-Ada complex. The electride nature of M3O-Ada complexes is confirmed through their electron density distribution and their energy gaps (2.19–3.06 eV) are reduced significantly. Interestingly, the absorption maxima (1387–1629 nm) of M3O-Ada electrides fall in the near infrared region. The highest first and second hyperpolarizability values of 5.9 × 105 au and 2.6 × 108 au are observed for K3O-Ada electride. The maximum hyper-Rayleigh scattering and second harmonic generation values of 1.3 × 107 au and 6.5 × 106 au are obtained at 1907 nm whereas the electro-optical Pockel's effect (6.5 × 106 au) is maximum at 1064 nm. Moreover, the dynamic second hyperpolarizability co-efficients (EOKE, EFISHG) are also computed at varying wavelengths. The M3O-Ada electrides exhibit the maximum nonlinear refractive index n2 of 1.9 × 10−7 cm2 W−1 at 1064 nm. This study will pave the way to the designing of stable superalkali doped diamondoids with enhanced NLO response.

{[In2S7]8–}∞ Chain and Isolated HgS4 Planar Unit Constructed One-Dimensional Pentanary Sulfide K2Ba7HgIn4S16 Exhibiting Nonlinear-Optical Activity

Hg-based chalcogenides possess diverse structures, large nonlinear-optical (NLO) responses, and suitable birefringences, making them potentially suitable for numerous crucial criteria of practical application as infrared (IR) NLO crystals. Here, a new pentanary Hg-based sulfide K2Ba7HgIn4S16 has been discovered by a high-temperature solid-state method. It crystallizes in the orthorhombic P21212 space group, and its one-dimensional structure is constructed by {[In2S7]8-}∞ chains and isolated [HgS4]6- planar quadrilateral units located bewteeen the chains, representing a novel type of chalcogenide. K2Ba7HgIn4S16 exhibits a moderate NLO effect of 0.5 × AGS at 2.1 μm and a high laser-induced damage threshold of ∼5.8 × AGS, as well as a band gap of 2.98 eV, demonstrating that K2Ba7HgIn4S16 is a potential IR NLO material. This work enriches the structural chemistry of chalcogenides and the family of Hg-based IR NLO chalcogenides.

Structural, optical, magnetic and thermal properties of L-methionine succinic acid single crystal for photonic applications

Growth and characterization of organic non-linear optical materials have accomplished tremendous standpoints whereby they perceive a wide range of applications compared to the inorganic materials because of the spectacular applications. In fact, the process of searching for potential non-linear optical materials is still in the active race even though a large number of materials have been reported over the years. In the present work, an amino acid-based single crystal of doped l-Methionine Succinic Acid (LMS) was grown by slow evaporation method at room temperature and its physio-chemical properties are reported here. The crystallographic structure and the lattice parameters of the grown crystal are studied by the Single Crystal XRD method. The undertaken UV–Visible Spectral analysis confirms that the LMS crystal is suitable for various optical applications due to its wide optical transmittance window extending throughout the visible region. The presence of the functional groups has been estimated by employing the FTIR technique. The outcome of the VSM study reveals that LMS crystal belongs to the category of soft magnetic materials.

Covalent Organic Frameworks as Emerging Nonlinear Optical Materials.

The vastness of organic synthetic strategies and knowledge of reticular chemistry have made covalent organic frameworks (COFs) one of the most chemically and structurally diverse class of materials with potential applications ranging from gas storage, molecular separation, and catalysis to energy storage and magnetism. Recently, this class of porous materials has garnered increasing interest as potential nonlinear optical (NLO) materials. Traditionally, inorganic crystals, small-molecule organic chromophores, and oligomers have been studied for their NLO response. Nevertheless, COFs offer significant advantages over existing NLO materials in terms of higher mechanical strength, thermochemical stability, and extended conjugation. Herein, we discuss crucial aspects, terminology, and measurement techniques related to NLO, followed by a critical analysis of the design principles for COFs with NLO response. Furthermore, we touch on selected potential applications of these NLO materials. Finally, future prospects and challenges of COFs as NLO materials are discussed.

Covalent Organic Frameworks as Emerging Nonlinear Optical Materials

AbstractThe vastness of organic synthetic strategies and knowledge of reticular chemistry have made covalent organic frameworks (COFs) one of the most chemically and structurally diverse class of materials with potential applications ranging from gas storage, molecular separation, and catalysis to energy storage and magnetism. Recently, this class of porous materials has garnered increasing interest as potential nonlinear optical (NLO) materials. Traditionally, inorganic crystals, small‐molecule organic chromophores, and oligomers have been studied for their NLO response. Nevertheless, COFs offer significant advantages over existing NLO materials in terms of higher mechanical strength, thermochemical stability, and extended conjugation. Herein, we discuss crucial aspects, terminology, and measurement techniques related to NLO, followed by a critical analysis of the design principles for COFs with NLO response. Furthermore, we touch on selected potential applications of these NLO materials. Finally, future prospects and challenges of COFs as NLO materials are discussed.

Structure and Characterization of K2Na3B2P3O13, a New Nonlinear Optical Borophosphate with One-Dimensional Chain Structure and Short Ultraviolet Cutoff Edge.

Nonlinear optical (NLO) crystals, being the primary medium for laser wavelength conversion, are crucial in all-solid-state lasers. Borophosphates offer more structural varieties than pure borates and phosphates, and they have become popular as NLO crystal candidates. Through spontaneous crystallization, we acquired a noncentrosymmetric alkali metal borophosphate crystal material, K2Na3B2P3O13 (KNBPO). KNBPO crystallizes in the orthorhombic Cmc21 space group with the following unit cell parameters: a = 13.9238(18) Å, b = 6.7673(8) Å, c = 12.1298(15) Å, and Z = 4, and its structure is characterized by a fundamental building unit 1∞ [B2P3O13] chain structure made up of bridging oxygen linkages between BO4 and PO4 tetrahedra. KNBPO has a short ultraviolet (UV) cut-off edge (<186 nm), a congruent melting characteristic, good thermal stability, and a moderate second harmonic generation response roughly 0.42 times that of KH2PO4. Theoretical calculations reveal that the optical properties of the compound mainly originate from BO4 and PO4 units. Due to the short UV cut-off edge, KNBPO can be used as a potential NLO material in the UV and even deep UV regions, and it enhances the structural variety of borophosphates, which has a reference value for scholars investigating similar materials.

BN-Doped Carbon Nanotubes and Nanoribbons as Nonlinear-Optical Functional Materials for Application in Second-Order Nonlinear Optics

Pure carbon-based nanomaterials with good π conjugation and thermal stability, e.g., nanotubes and nanoribbons, have long served as promising conjugated materials for application in second-order nonlinear-optical (NLO) devices but suffer from two inherent structural problems: weak polarity (or even nonpolarity) and high chemical reactivity ascribed to zigzag edge states. In the present work, boron nitride (BN) chains are used to divide carbon nanotubes and nanoribbons, forming a functional block to tune the electronic structure, and thus induce charge redistribution or modify the molecular energy gap for second-order NLO materials or integrated electronic materials. A balance between the electronic kinetic stability and second-order NLO properties is established by structural manipulation. The strong second-order NLO responses in the visible and near-infrared regions make these hybridized carbon-based molecules potential NLO materials for applications in biological nonlinear optics. The application of BN to tune the electronic structure of carbon nanomaterials paves a path for fabricating nanoelectronic and nano-NLO devices.

SYNTHESIS, SPECTRAL, QUANTUM CHEMICAL METHOD, In-silico MOLECULAR DOCKING, AND ADMET ANALYSIS OF (E)-ISOBUTYL 2-(2-(4-CHLOROPHENYL) HYDRAZONO)-3- OXOBUTANOATE DERIVATIVES

The synthesis of (E)-isobutyl2-(2-(4-chlorophenyl)hydrazono)-3-oxobutanoate derivatives has been achieved by condensation of 4-chloroaniline and isobutyl 3-oxobutanoate using benzene diazonium chloride. Physicochemical and spectroscopic methods such as IR, 1H-NMR, 13C-NMR, and melting point measurements were used for the examination of the synthesized compound. Density functional theory was used along with the basic set of B3LYP/6- 311 G (d, p) for optimizing the geometrical structure. The stability of the molecule as well as charge delocalization was examined using natural bond orbital analysis. The frontier molecular orbital energies give a description of the transfer of charge that occurs within the molecule. Analysis has been done on molecular electrostatic potential. Since the reported molecule has a high hyperpolarizability value, it is considered a potential nonlinear optical material. To conduct studies on drug similarity and oral activity, Lipinski's rule of five was used. The binding energy of the drug to several Covid receptors is examined using molecular docking experiments and it is determined that this compound is a superior antiviral agent.

AIO3·H6TeO6 (A = NH4+, Rb+): Two telluric acid and iodate Co-crystalline compounds with second harmonic generation response

Two co-crystalline compounds containing telluric acid and iodate, namely AIO3·H6TeO6 (A ​= ​Rb+, NH4+), were investigated as potential nonlinear optical materials. They crystallize into isostructural and consist of isolated [IO3] group and [H6TeO6] molecule linked by hydrogen bonds and charge interactions of Rb+/NH4+. They show phase-matching second harmonic generation responses with moderate intensity of 1.2 ​× ​KDP (Rb+) and 1.1 ​× ​KDP (NH4+). They also possess large optical band gaps over 4.25 ​eV and can be easily grown from aqueous solutions. The local dipole moment calculations based on the structures of AIO3·H6TeO6 (A ​= ​K+, Rb+, NH4+) series of compounds indicate that the change of A+ cation in their structural frame causes a slight change in the arrangement directions of [IO3] and [Te(OH)6] groups, and further induces their SHG responses of different intensities at the macroscopic level.

Enhanced non-linear optical properties of porphyrin-based polymers covalently functionalized with graphite phase carbon nitride.

In our work, a flurry of original porphyrin-based polymers covalently functionalized g-C3N4 nanohybrids were constructed and nominated as PPorx-g-C3N4 (x = 1, 2 and 3) through click chemistry between porphyrin-based polymers with alkyne end-groups [(PPorx-C≡CH (x = 1, 2 and 3)] and azide-functionalized graphitic carbon nitride (g-C3N4-N3). Due to the photoinduced electron transfer (PET) between porphyrin-based polymers [PPorx (x = 1, 2 and 3)] group and graphite phase carbon nitride (g-C3N4) group in PPorx-g-C3N4 nanohybrids, the PPorx-g-C3N4 nanohybrids exhibited better non-linear optical (NLO) performance than the corresponding PPorx-C≡CH and g-C3N4-N3. It found that the imaginary third-order susceptibility (Im [χ(3)]) value of the nanohybrids with different molecular weight (MW) of the pPorx group in the nanohybrids ranged from 2.5×103 to 7.0 × 103gmol-1 was disparate. Quite interestingly, the Im [χ(3)] value of the nanohybrid with a pPorx group'sMW of 4.2 × 103gmol-1 (PPor2-g-C3N4) was 1.47 × 10-10 esu, which exhibited the best NLO performance in methyl methacrylate (MMA) of all nanohybrids. The PPorx-g-C3N4 was dispersed in polymethyl methacrylate (PMMA) to prepare the composites PPorx-g-C3N4/PMMA since PMMA was widely used as an alternative to glass. PPor2-g-C3N4/PMMA showed the excellent NLO performance of all nanohybrids with the Im [χ(3)] value of 2.36 × 10-10 esu, limiting threshold of 1.71J/cm2, minimum transmittance of 8% and dynamic range of 1.09 in PMMA, respectively. It suggested that PPorx-g-C3N4 nanohybrids were potential outstanding NLO materials.