Solid-state UV Research Articles

Lead-free semiconductor materials with high phase transition temperature: [1-Methylimidazole][SbBr4]

Semiconductor with structure phase change is a special multi-functional material, which plays an important role in the field of Solar Energy, information computing, sensor technology, artificial intelligence, etc. In this paper, the organic–inorganic lead-free semiconductor phase change material [1-Methylimidazole][SbBr4] (1) was successfully constructed. The IR, TGA, DSC, VT-PXRD, solid-state UV–vis spectroscopy and temperature dependence of dielectric constant were characterized and analysed. Single crystal X-ray diffraction shows that at 298 K, the space group is P21/c, the point group 2/m; an endothermic and exothermic peak appeared near 386 K and 367 K in the DSC heating–cooling cycles. Near the corresponding phase transition temperature point, compound 1 exhibits a significant reversible change in the dielectric platform. Interestingly, the band gap of compound 1 is about 2.53 eV. The existence of such interesting physical properties is closely related to the interaction between cations and anions in the molecule and the connection of internal hydrogen bonds. By constructing organic–inorganic hybrid semiconductor materials, we hope to obtain semiconductor materials with phase transition properties and actively explore and provide some ideas and support for the application of new high-tech materials.

Synthesis, structure and characterization of two new silver-iron based phosphates AgFe2(PO4)2F(H2O)2 and Ag3Fe2(PO4)(HPO4)3

Two new silver-iron based phosphates AgFe2(PO4)2F(H2O)2 (1) with monoclinic P21/n and Ag3Fe2(PO4)(HPO4)3 (2) with triclinic P-1 were synthesized by a conventional hydrothermal method, featuring a dimer structure and a twisted honeycomb-like lattice, respectively. XPS and BVS (Bond Valence Sum) calculations indicated only Fe3+ ions in both compounds, while FT-IR spectra proved the presence of [H2O] in 1 and [OH] groups in 2. Solid-state UV–vis–NIR diffuse reflectance spectra suggested their wide optical band gaps of 2.31 eV and 1.94 eV, respectively. Magnetic measurements indicated that both compounds display a long-range antiferromagnetic ordering at low temperature, showing the change of magnetic entropy of 9.59 J mol−1 K−1 in 1 and that of 14.87 J mol−1 K−1 in 2, respectively.

Hydrothermal preparation, crystal structure, Hirshfeld surface analysis, photophysical properties and antifungal activity of a series of complexes assembled by 5-bromo-2-(carboxymethoxy)benzoic acid ligands

Five complexes [Co(BCBA)(H2O)3]n (1), [Co(BCBA)(4,4′-Bipy)2·(H2O)]n (2), [Cu(BCBA)(H2O)]n (3), [Zn(BCBA)(H2O)]n (4) and [Cd(BCBA)(2,2′-Bipy)(H2O)·(H2O)]n (5) (H2BCBA= 5‑bromo-2-(carboxymethoxy)benzoic acid, 4,4′-Bipy = 4,4′-bipyridine and 2,2′-Bipy = 2,2′-bipyridine) have been synthesized with H2BCBA ligand by solvothermal condition. All the complexes have been structurally characterized by infrared spectra (IR), elemental analyses and single-crystal X-ray diffraction analyses. Complex 1 is a zero-dimensional structure, and complexes 2–5 are one-dimensional chain structure. Furthermore, thermogravimetric analyses (TGA), Hirshfeld surface analysis, photo-luminescence properties, Solid-state UV–Vis diffuse reflectance spectroscopy and antifungal activity for complexes 1–5 were investigated. The reciprocal H···O/H/Br/C contacts dominate over 86 % of total Hirshfeld surface. Complexes 1–5 have certain inhibitory effects on 8 pathogenic fungi. Among them, complex 5 has the strongest antibacterial activity against Rhizoctonia solani AG1, Sphaeropsis sapinea and Colletotrichum fructicola, and the inhibitory rate reached 100 %.

Structural features and DNA binding ability of SBA-15 nanostructured silica containing amino acids or amino acid-derived drugs grafted with vanadocene complexes

Novel silica nanostructured materials, synthesized by functionalizing SBA-15 with amino acids or amino acid-derived drugs and vanadocenes, have been meticulously characterized using a range of spectroscopic and thermal techniques. Employing FTIR, solid-state UV–vis, XRF, XRD, and TGA analyses, we have unequivocally confirmed the successful functionalization of the silica carriers. The incorporation of our target molecules predominantly occurred within the pores of these silica-based systems, as evidenced by the discernible reduction in peak intensities in the corresponding diffractograms post-functionalization. Complementing these findings, solid-state 51V NMR investigations suggest a four-coordinated local symmetry around V in the final materials (S6–S8). Additionally, we conducted qualitative DNA binding tests on S7, which yielded compelling results indicating DNA adherence to the surfaces of the metallodrug-functionalized nanomaterials. In light of these results, our proposed nanosystems exhibit significant promise as potential anticancer agents.

Combined experimental and theoretical studies of some uranium(VI) complexes derived from imidazole-based carbenes

A series of bidentate, viz., 1,1'-(1,2-ethylene)-3,3'-dimethyldiimidazoline-2,2'-diylidene (L1), 1-methyl-3-(2-pyridylmethyl)-imidazoline-2-ylidene (L2) and tridentate, viz., 1,3-bis(2-pyridyl)-imidazoline-2-ylidene (L3) ligands have been obtained from their corresponding imidazolium salts through deprotonation reactions. Treatment of UO2Cl2(THF)3 with one equivalent L3 produces air-stable U(VI)-carbene complex 3, characterized by elemental analysis, FTIR, NMR spectroscopy as well as extended X-ray absorption fine structure (EXAFS) analysis. EXAFS result indicates that the ligand is bonded through one C and two N-atoms to the uranium atom. Attempts to synthesize uranyl complexes derived from L1 and L2 were also successful but these complexes are decomposed quickly within one hour at room temperature. 3 produces pure UO2 powder when heated under an argon atmosphere from room temperature to 600 °C with constant heating rate of 5 °C/min. The solid-state UV–Vis spectrum of the compound shows absorption peaks at 332 and 450 nm. The excitation spectrum of 3 (at λ em = 520 nm) exhibits two almost symmetrical peaks at 273 and 368 nm. Density functional theory-based quantum mechanical calculations indicate that a partial covalent interaction exists between the carbene C and U while a weak non-covalent interaction exists between carbene N and U atoms.

Co(1-nSr)TiO3 (n=0, 0.05, 0.1) nano perovskites: Novel photocatalysts synthesized by sol-gel and cold-evaporated sol-gel methods for CO remediation from polluted air

The cobalt-based perovskite photocatalysts doped with three strontium levels, Co(1-nSr)TiO3 (n = 0, 0.05, 0.1), were synthesized using sol-gel (SG) and cold-evaporated sol-gel (CESG) methods and their photocatalytic performance were compared in the field of photocatalytic CO remediation from polluted air. The photocatalytic samples were evaluated by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, solid-state UV spectroscopy, scanning electron microscopy (SEM), Transmission electron microscope (TEM), and BET surface area to evaluate physicochemical properties and their correlation with activity. The results showed that the cold-evaporated synthesis reduced the bandgap and increased the photocatalytic activity. The cold-evaporated synthesis technique enhanced the bandgap range by 15% through 0.05% Sr doping (from 3.3eV at CoTiO3 to 2.85 eV at Co(1-0.05Sr)TiO3, where wavelength activity decreased from 375.97 nm (UV region) to 435.33 nm (visible region). The optimum photocatalyst, Co(1-0.05Sr)TiO3 (CESG) exhibited 62.6% CO oxidation under the visible region. The result demonstrated that the CESG synthesis method increases the surface area, decreases the particle size, narrows and uniforms particle size distribution, and changes the crystal structure compared to the SG method. It is concluded that the CESG method is a promising method to synthesize photocatalysts that are activated under visible light for environmental protection.

High energy and average power solid-state UV laser for industrial applications

High energy and average power solid-state UV laser involves several challenges to manage degradation due to UV radiations. Recent results achieved in this direction are presented.

Ratiometric luminescent sensor based on BSA-coated gold/silver nanoclusters for the selective determination and spatiotemporal imaging of gallic acid in plants.

Anewfluorescence sensing strategyhas been developed. Four bimetallic nanoclusters, gold/silver, gold/copper, gold/molybdenum and gold/cobalt, were prepared using bovine serum albumin (BSA) as a reducing and stabilizing agent. The fluorescence properties of four nanoclusters were explored by solid-state UV and XPS. The gold/silver nanoclusters (BSA-Au/Ag NCs) with the best ratiometric fluorescence properties for gallic acid (GA) in plants were selected to realize the sensitive detection of GA. GA affected the conformation of BSA, thereby disrupting the luminescent environment of the nanoclusters, resulting in a pronounced fluorescence quenching at 566nm. The ratiometric fluorescence signal (I566/I453) was used for trace detection of GAin plants. It has a wide response range of 1.25-40.0μM and a low detection limit of 45.27nM. GA was detected at 19.49μM in the plant extract, and the spiked recoveries ranged from 96.09 to 104.6%. In addition, due to the non-toxic and biocompatible properties of BSA, BSA-Au/Ag NCs have also been validated for fluorescence imaging of plant tissues. It realized the comparison of GA content in different parts of plants and the difference of GA content in plants after abiotic stress. Therefore, the developed strategy offers potential application for the analytical study of active substances in plants.

A new zero-dimensional (0D) hybrid bismuth (III) halide: Synthesis, crystal structure, thermal analysis, photophysical properties and DFT calculations

Low-dimensional organic-inorganic hybrid Bi(III) halides, with organic N, O-heterocycles, are promising solid-state photoluminescent materials, but are underexplored. In this work, we present the synthesis and characterization of a novel bismuth (III) hybrid salt, namely (C8H12NO)4[Bi2Cl10] (referred as (1)). (1) was synthesized using a solvent-evaporation method and extensively characterized using various techniques. The crystal structure of (1) was determined to be zero-dimensional (0D). In this structure, the individual bioctahedral [Bi2Cl10]4− dimers, which share edges, are completely isolated from each other. These dimers are separated by large 4-methoxybenzylammonium cations (C8H12NO)+. The latter are crucial for the crystal structural stability by balancing [Bi2Cl10]4-dimer charges and maintaining overall integrity. Solid-state diffuse reflectance UV–Vis spectrum demonstrates that (1) is a semiconductor with a band gap of 3.32 eV. Its photoluminescence spectrum exhibits intense blue emission when exposed to UV light, with CIE chromaticity coordinates of (0.22, 0.21). Theoretical calculations suggest that the emission with multiple centers originates both from a charge transition between (C8H12NO)+ and Bi2Cl104− ions and from excited-state proton transfer (ESPT) processes related to fluorescence properties. These ESPT processes occur through C–H…π and C–H…O intermolecular hydrogen bonding between the organic cations.

Self-powered MSM solar-blind AlGaN photodetector realized by in-plane polarization modulation.

Solid-state self-powered UV detection is strongly required in various application fields to enable long-term operation. However, this requirement is incompatible with conventionally used metal-semiconductor-metal (MSM) UV photodetectors (PDs) due to the symmetric design of Schottky contacts. In this work, a self-powered MSM solar-blind UV-PD was realized using a lateral pn junction architecture. A large built-in electric field was obtained in the MSM-type UV-PD without impurity doping, leading to efficiency carrier separation and enhanced photoresponsivity at zero external bias. The solar-blind UV-PD exhibits a cutoff wavelength of 280 nm, a photo/dark current ratio of over 105, and a responsivity of 425.13 mA/W at -10 V. The mechanism of self-powered UV photodetection was further investigated by TCAD simulation of the internal electric field and carrier distributions.

Development of pyrene-based MOFs probe for water content and investigations on their mechanochromism and acidochromism

A smart fluorescent pyrene-based MOFs (HPU-26) was synthesized by the solvothermal method, which possessed multi-stimuli-responsive properties and could detect water content in common organic solvents. The reversible multicolor fluorescent switching between yellowish green and cyan were observed under the stimulation of force, heating, and acid-base vapors. PXRD pattern, DSC curve, FI-IR spectra and the solid-state UV–vis absorption spectra were conducted to prove that the changes of π - conjugation induced the transformations between excimer and monomer formation under external stimulation, thus resulting in different fluorescent properties. In addition, HPU-26 could realize the detection of water content by remarkable change of fluorescent color from yellowish green to blue with increasing the water content in common organic solvents, which was attributed to the decomposition of crystal structure. The limit of detection (LOD) values of HPU-26 for detecting the water content in EtOH, DMA, Acetone and ACN were determined as 0.0260 %, 0.0578 %, 0.1978 %, and 0.5637 % (v/v), respectively. Furthermore, HPU-26 could be applied in advanced anti-counterfeiting and convenient visual detection of water content in common organic solvents by smartphone-based software.

Anion Dependent Coordination Polymers of Different Copper Salts with Mixed Organic Ligands (bis(4‐Nitrophenyl)phosphoric Acid and 4,4′‐Bipyridine)

AbstractDifferent coordination polymers that are prepared by using various copper salts with diverse counter ions (perchlorate/ nitrate/ acetate/ iodide) along with bis(4‐nitrophenyl)phosphoric acid (BNPP) and 4,4′‐bipyridine (bpy) have been reported. In each case, two distinct coloured crystals (royal and cyan blue) are observed, concomitantly. The composition and structural features of royal blue crystals are the same in all structures irrespective of counter ions employed, yielding a distorted square pyramid structure with each copper metal ion coordinated to one BNPP and four bpy molecules along with six water molecules in the lattice. However, the compositions of the cyan blue crystals are different depending on the counter ions used. Thus, copper metal ion was found in distinct coordination spheres in each structure. For example, perchlorate anion produces a mixed geometry structure {[Cu(BNPP)2(bpy)2(H2O)][Cu(bpy)2(H2O)2]}ClO4 containing two Cu(II) metal ions with independent square pyramid and square planar geometries along with an uncoordinated perchlorate anion. In addition, it also gives a structure with a molecular formula [Cu2(BNPP)5(bpy)3], devoid of perchlorate ions, having two different Cu(II) coordination spheres (square pyramid and square planar), which are connected together. In contrast, with nitrate ions, cyan blue crystals form a square pyramidal geometry with the formula [Cu(BNPP)2(bpy)2(NO3)], in which the anion is coordinated to Cu(II) ions. Furthermore, with acetate ion, two different complexes having formulae [Cu(BNPP)2(bpy)2] ⋅ 2H2O and [Cu(bpy)2(acetate)2](H2O)2(nitrophenol) are observed, with the latter complex is formed possibly due to the facile hydrolysis of BNPP molecules yielding a nitrophenol. In both the complexes Cu(II) projects a square planar geometry. However, in the case of iodide anion, a complex [Cu2(BNPP)5(bpy)3] ⋅ 2H2O is formed, without any anion, in which two distinct Cu metal ions with tetra‐ and penta‐coordinated spheres are connected together through bpy molecules and yield square planar and square pyramid geometries. The structures of these coordination polymers are thoroughly characterised by single crystal X‐ray diffraction and spectroscopic methods (IR, solid state UV and photoluminescence).

Phenol-Tethered N-Heterocyclic Benzimidazol-2-ylidene Carbene Interactions with the Early Lanthanides

The cyclization of salophan with triethyl orthoformate in the presence of HBr results in a bisphenol benzimidazolium carbene precursor 1,3-bis(2-hydroxybenzyl)-2H-benzimidazolium bromide (H3OBBIm). By reacting H3OBBIm in a one-pot synthesis with Ln(N(SiMe3)2)3 (Ln = La–Sm excl. Pm) and an excess of KN(SiMe3)2, the N-heterocyclic carbene (NHC) complexes, [Ln(OBBIm)2(N″)][K2THFx], can be prepared and isolated. These complexes were characterized by single-crystal X-ray diffraction, solution- and solid-state UV–vis–near-infrared spectroscopy, and 1H NMR. These complexes possess distorted pentagonal bipyramid geometries.

The copper(II) coordination chemistry of alkyl substituted bispyrazole pyridine ligands: Structure and spectral properties

Tridentate, planar nitrogen containing ligands based on pyridine and pyrazoles were synthesized by the reaction of 2,6-dibromopyridine with the sodium salts of 3,5-dimethylpyrazole and 3,5-diisopropylpyrazole to yield 2,6-bis(3,5-dimethyl-N-pyrazolyl)pyridine (L0py) and 2,6-bis(3,5-diisopropyl-N-pyrazolyl)pyridine (L1py), respectively. The conformation of the pyrazole rings in the solid-state structures of both L0py and L1py were anti due to relatively low repulsion between the alkyl substituents. Both copper(II) chlorido complexes [CuCl2(L0py)] and [CuCl2(L1py)] were five-coordinate with solid-state structures best described as distorted square-pyramidal geometry involving N3Cl2 donor sets. The ν(Cu–Cl) energies and Cu–Cl bond lengths were clearly different due to the different donating properties of the two ligands. By comparison, the structure of copper(II) trifluoromethanesulfonato complex [Cu(OTf)2(H2O)(L1py)] was six-coordinate with highly distorted octahedral geometry involving an N3O3 donor set. The solution UV–Vis spectra of [CuCl2(L0py)], [CuCl2(L1py)], and [Cu(OTf)2(H2O)(L1py)] revealed π-π* transition bands red-shifted by ∼30 nm on complexation. The d-d transition bands of all three copper(II) complexes were observed at almost the same energy of ∼750 nm, while the corresponding solid-state UV–Vis spectra exhibited absorptions at ∼1010 nm and 674 nm due to differences in coordination geometry. These structural changes in the solution-state were supported by results from EPR spectroscopy.

Syntheses, characterization of three new cobalt(II) complexes with 2-phenylsuccinic acid and flexible bis(imidazole) linkers

Bis(imidazole) derivatives (obix, mbix, pbix = 1,2-/1,3-/1,4-bis((imidazol-1-yl)methyl)benzene) with Co(II) and flexible 2-phenyl succinic acid (phsucH2) afforded three coordination polymers namely, [Co(µ-phsuc)(µ-obix)]n (1), {[Co(µ-phsuc)(µ-mbix)]⋅H2O}n (2), {[Co(µ4-phsuc)(µ-pbix)0.5]⋅H2O}n (3) and they were characterized by elemental analysis, magnetic susceptibility, solid-state UV–Vis. and IR spectroscopies and single crystal X-ray diffraction techniques. The phase purities of the complexes were confirmed by powder X-ray diffraction analysis. X-ray diffraction studies have shown that compounds 1 and 2 crystallize in the monoclinic system, in the P21/c space group, while compound 3 crystallizes in the P-1 space group in the triclinic system. In all compounds, bis(imidazole) ligands act as bis(monodentate), whereas 2-phenylsuccinate ligands act as both monodentate and bidentate bridges in 1, bis(monodentate) bridges in 2, tetrakis(monodentate) bridges in 3. The complexes displayed 2D layer structures and adjacent 2D layers are joined by C–H···π interactions in 1, weak C–H···O interactions in 2, π···π stacking and weak C–H···π interactions in 3 to form a 3D supramolecular network. The contribution of the binding positions of the imidazole groups to the phenyl ring in bis(imidazole) ligands to the structure and structural diversity are also discussed. In addition, the thermal properties of the compounds were investigated in the study.

Heterometallic Mo–Ti oxo clusters with metal–metal bonds: Preparation and visible-light absorption behaviors

In this work, two heterometallic clusters, namely Ti^IV₄Mo^V₄Mo^VI₂O₁₆(OCH₃)₁₆ (<strong>1</strong>) and Ti^IV₄Mo^V₄O₁₀(OC₂H₅)₁₄ (C₆H₅COO)₂ (<strong>2</strong>) are successfully constructed to improve the solar absorption and performance of titanium oxo clusters (TOCs). The <strong>1</strong> and <strong>2</strong> structures are determined well by single-crystal X-ray diffraction analysis and found to feature the common presence of Mo–Mo interactions. The solid-state UV–vis absorption studies indicate that these structures exhibit enhanced visible-light absorption and significantly reduced optical band gaps, which should be dominantly attributed to the introduction of electron-rich Mo–Mo pairs as heterometals. This work demonstrates an effective strategy of regulating the light absorption behaviors of TOCs by importing electron-rich heterometals.

New Low-Dimensional Organic–Inorganic Lead Halide Hybrid Systems Directed by Imidazo[1,5-a]pyridinium-Based Cation or Imines: Synthesis, Structures, Non-Covalent Interactions and Optical Properties

The organic–inorganic lead halide hybrids comprising semiconducting perovskite components and organic modules have proven to be promising candidates for optoelectronic applications. The modulation of the inorganic components as optical centres by diverse organic cationic templates is under intense investigation. Herein, we successfully prepared new one-dimensional lead halide hybrid perovskites [L1]2n[Pb2Cl6]n∞·nH2O (1) and [PbBr2(L2)]n∞·0.5nH2O (2), and the dimeric complex [PbBr2(L3)]2 (3) in water media. In 1, 2-(2-hydroxyethyl)-2H-imidazo[1,5-a]pyridinium cation [L1]+ resulted from the oxidative condensation–cyclization between formaldehyde, ethanolamine and 2-pyridinecarbaldehyde (2-PCA); the polydentate Schiff base ligands L2 and L3 formed in the in situ condensation of 2-PCA and ethanolamine or ethylenediamine, respectively. The lead chloride hybrid 1 contains the previously unreported type of a [Pb2Cl6]∞ double chain constructed from three-edge- and five-edge-sharing PbCl6 octahedra, and cations forming π-bonded stacks aligned along the inorganic wires. In the crystal of 2, pairs of the double-side organically decorated [PbBr2(L2)]∞ chains built of corner-sharing PbBr3N2O octahedra arrange hydrophilic channels to host water molecules. In the solid state, the identically stacked dimers of 3 form columns parallel to the ab plane with the Pb2Br4 moieties in the column being strictly coplanar. Hirshfeld surface analysis was used to rationalize the packing patterns through hydrogen bonds of O−H···O/Cl and C−H···O/Cl types with the involvement of OH groups of [L1]+, L2 and water molecules in 1 and 2, as well as C–H∙∙∙Br hydrogen bonding in 2 and 3. The QTAIM analysis of non-covalent interactions in 1–3 was performed. According to the analysis of the solid-state UV–visible reflectance spectra by a Tauc plot, the optical band gap values of 1, 2 and 3 as direct gap semiconductors were estimated to be 3.36, 3.13 and 2.96 eV, respectively.

레이저 유도 전사를 이용한 유연기판의 액체금속 미세 패터닝

We have developed a direct conductive patterning method with micro-scale line widths using the laser-induced-forward transfer (LIFT) and liquid metal. As this method does not need post-thermal processing, there is no thermal damage even on heat-sensitive polymer substrates by low-power laser irradiation on the dynamic release layer (DRL). Unlike other liquid metal patterning processes, this procedure can easily achieve fine line widths of a few tens of micrometers corresponding to laser spot size. The solid-state UV pulse laser with 266 nm wavelength and 20 ns pulse duration was used to transfer Eutectic Gallium Indium (EGaIn) liquid metal and the results for the single and multi-pulse laser irradiation were investigated to determine the effective process conditions. The applicability of flexible circuit fabrication and selective circuit repair was successfully tested on Polyimide (PI) substrate. After the LIFT process, the electrical properties of liquid metal on the pattern were measured to be approximately 5~8 x 10SUP-3/SUP Ω/m of resistance.

Efficient Photothermal Energy Conversion Triggered by near-Infrared Light in a Dithiolene-Based Metal–Organic Framework

A Ni-dithiolene ligand, {Ni(pedt)2}− (pedt = 1-(pyridine-4-yl)ethylene-1,2-dithiolate), was used to prepare a novel interpenetrated redox-active Metal–Organic Framework (MOF), which exhibited an efficient photothermal conversion under low-power-density near-infrared (NIR) laser illumination. Solid-state UV–vis-NIR spectroscopy on bulk crystals indicated strong absorbance in the NIR region, attributed to the radical monoanion of the pedt ligands, which was also evident in the solid-state Electron Paramagnetic Resonance (EPR) spectrum. DFT computations on a model system provided new insights into the structural factors underpinning the photothermal properties. First, the NIR absorption corresponds to a high-energy excited state (D4), while the lowest-lying excited state (D1) is close in energy to the energies of the vibrational motions, facilitating the conversion of electronic to thermal energy. Second, close contacts between interpenetrated nets of the MOF may further enhance the propagation of thermal motion. The new photothermal MOF was then doped into a self-healing polymer, PDU (polydimethylsiloxane-urea), leading to composites which could recover from dynamic damage using the heat generated from the embedded MOF by photostimulus. This process led by the photothermal effect offers a highly efficient and energy-saving approach for self-healing materials design.

Evaluation of Photostability of Small Molecular Compounds with Solid-state UV Spectra

It is crucial to evaluate the photostability of drugs. However, it requires a longer period of time to evaluate the photodegradation of compounds because extended light exposure to the compound is required to detect photodegradation products with the help of the commonly utilized technique of chromatography. Therefore, a simple and easy approach to estimate the photostability of the compound is required particularly for the initial screening of the drug candidates. It was reported in our previous manuscript that, focusing on ultraviolet-visible (UV/vis) spectrometry, the area under the spectrum curve in the ultraviolet-A (UVA) range (AUSCUVA) are closely related to the photodegradation of indomethacin polymorphs. In this study, the solid-state UV/vis absorption spectra of compound A polymorphs, indomethacin complexes and some small molecule compounds were determined and analyzed to check the applicability of this method. AUSCUVA are closely related to the photodegradation of compound A polymorphs as well as indomethacin. On the contrary, no close relation was observed between AUSCUVA of indomethacin complexes and their photodegradation. Additionally, the result indicated that the differences in their solid-state UV/vis absorption spectra were observed between photosensitive and photostable compounds. Photosensitive compounds show absorption in UVA range, while photostable compounds exhibit less absorption. In conclusion, the solid-state UV/vis absorption spectra of small molecular compounds might provide the key information on the photosensitivity.