E-beam synthesized fast-switching TiO2/SnO2 type-II heterostructure photodetector

A fast-switching T i O 2/S n O 2 heterostructure thin-film (TF) photodetector synthesized by electron beam evaporation technique is analyzed in this study. The substrate utilized is n-type silicon (Si), while gold (Au) is employed as the top electrode. To assess sample morphology and confirm elemental composition, field emission scanning electron microscopy (FESEM), energy dispersive x-ray spectroscopy (EDS), and chemical mapping were conducted. Structural characteristics were determined using X-ray diffraction (XRD) analysis. The XRD analysis confirmed the presence of various phases of T i O 2 (anatase and rutile) and S n O 2 (rutile). UV-Vis spectroscopy revealed multiple absorption peaks, at 447 nm, 495 nm, 560 nm, and 673 nm, within the visible spectrum. The device demonstrates high detectivity (D ∗) of 1.737×109 Jones and a low noise equivalent power (NEP) of 0.765×10-10 W. Evaluation of the device's switching response through current-time characteristic (I-T) analysis indicates rapid switching with a rise time and fall time of 0.33 s and 0.36 s, respectively.

Fabrication strategies for chiral self-assembly surface

Chiral self-assembly is the spontaneous organization of individual building blocks from chiral (bio)molecules to macroscopic objects into ordered superstructures. Chiral self-assembly is ubiquitous in nature, such as DNA and proteins, which formed the foundation of biological structures. In addition to chiral (bio) molecules, chiral ordered superstructures constructed by self-assembly have also attracted much attention. Chiral self-assembly usually refers to the process of forming chiral aggregates in an ordered arrangement under various non-covalent bonding such as H-bond, π-π interactions, van der Waals forces (dipole-dipole, electrostatic effects, etc.), and hydrophobic interactions. Chiral assembly involves the spontaneous process, which followed the minimum energy rule. It is essentially an intermolecular interaction force. Self-assembled chiral materials based on chiral recognition in electrochemistry, chiral catalysis, optical sensing, chiral separation, etc. have a broad application potential with the research development of chiral materials in recent years.

Electrical and Photodetector Characteristics of Schottky Structures Interlaid with P(EHA) and P(EHA-co-AA) Functional Polymers by the iCVD Method

In this study, poly(2-ethylhexyl acrylate) (PEHA) homopolymer and its copolymer combined with acrylic acid P(EHA-co-AA) were employed as interfaces in two separate Schottky structures. First, both interfaces were grown by initiated chemical vapor deposition (iCVD), which provides much better deposition control and homogeneous coating compared to solution-phase methods. In addition to this advantageous method, the effects of two different polymers, one of which is better able to adhere to the crystal surface on which it is formed than the other, on the optoelectronic properties have been studied. Then, their current-voltage (I-V) and capacitance/conductance-voltage (C/(G/ω)-V) characteristics were investigated both in the dark and under illumination. The basic electrical parameters and the illumination-induced profile of the surface state (Nss) were probed by I-V and C-V measurements for two samples. A decrease in the barrier height (BH) and, consequently, a significant increase in the photocurrent were observed under illumination. Striking changes in series resistance (Rs) values are also highlighted. The photocapacitance and conductance characteristics indicated that the structures could be considered not only as photodiodes but also as photocapacitors. Moreover, the voltage-dependent changes of some photodetector parameters, such as responsivity (R), sensitivity (S), and specific detectivity (D*), along with the transient photocurrent characteristics, are discussed for both structures. Therefore, we can say that the strong changes in these parameters, which figure the merit of photodiode and photodetector applications, depending on the voltage and under illumination, prove that it is a study carried out in accordance with the purpose and so they can be used in electronic and optoelectronic applications.

Coordination polymers: a promising candidate for photo-responsive electronic device application

The design and synthesis of electrically conductive coordination polymers (CPs) are of special interest due to their applications in the fabrication of many environmentally benign emerging technologies, such as molecular wires, photovoltaic cells, light emitting diodes (LEDs), field effect transistors (FETs) and Schottky barrier diodes (SBDs). Owing to their structural flexibility, easy functionality and adjustable energy levels, CPs are promising candidates for providing a better pathway for superior charge transport. Again, the utilization of visible light as an external stimulus to control and manoeuvre the electrical properties of the CPs is exceptionally motivating for the development of many optoelectronic devices, such as photodetectors, photo-switches, photodiodes and chemiresistive sensors. The applications of such materials in devices will solve questions regarding the energy crisis and environmental concerns. This study provides an overview of the recent advances in the development of photo-responsive CPs and the possibility of their application in developing optoelectronic devices. In this regard, a thorough literature survey was performed and the studies related to the fabrication of photosensitive conducting CPs for applications in optoelectronic devices are listed.

Liquid-assisted mechanochemical synthesis, crystallographic, theoretical and molecular docking study on HIV instasome of novel copper complexes: (µ-acetato)-bis(2,2'-bipyridine)-copper and bromidotetrakis(2-methyl-1H-imidazole)-copper bromide

In the present work the two new Cu(II) complexes, (µ-acetato)-bis(2,2'-bipyridine)-copper [Cu(bpy)2(CH3CO2)] and bromidotetrakis(2-methyl-1H-imidazole)-copper bromide [Cu(2-methylimid)4Br]Br have been synthesized by liquid assisted mechanochemical method. The [Cu(bpy)2(CH3CO2)] complex (1) and [Cu(2-methylimid)4Br]Br complex (2) characterised by IR and UV-visible spectroscopy and the structure are confirmed by XRD diffraction studies. Complex (1) crystallized in the Monoclinic with the space group of C2/c where a = 24.312(5) Å, b = 8.5892(18) Å, c = 14.559(3) Å, α = 90°, β = 106.177(7)° and γ = 90° and Complex (2) crystallized in the Tetragonal with the space group of P4nc, a = 9.9259(2) Å, b = 9.9259(2) Å, c = 10.9357(2) Å, α = 90°, β = 90° and γ = 90°. The complex (1) has distorted octahedral geometry where the acetate ligand showed bidentate bridging with the central metal ion and complex (2) has slightly deformed square pyramidal geometry. The HOMO-LUMO energy gap value and the low chemical potential showed that the complex (2) is stable and difficult to polarize compare to complex (1). The molecular docking study of complexes with the HIV instasome nucleoprotein showed the binding energy values - 7.1 and - 5.3 kcal/mol for complex (1) and complex (2) respectively. The negative binding energy values showed the complexes have affinity to bind with HIV instasome nucleoproteins. The in-silico pharmacokinetic study of the complex (1) and complex (2) showed non AMES toxicity, non-carcinogens and low honey Bee toxicity but weakly inhibit Human Ether-a-go-go-related gene.

Anion and solvent controlled growth of crystalline and amorphous zinc(ii) coordination polymers and a molecular complex

Controlled bottom-up synthesis of amorphous coordination polymers with tailored metal coordination is a research field in its infancy. In this study, synthesis control was achieved to selectively prepare one-dimensional (1D) crystalline and amorphous zinc(ii)-based coordination polymers and a dimeric molecular compound, all with similar coordination geometry as evidenced by X-ray diffraction and total scattering studies. The compounds were obtained by bottom up self-assembly of Zn(ii) with terephthalate (tph^2-) as linker and the enantiopure chelating ligand S-(1,2)-bis(1H-benzimidazol-2-yl)ethanol (L). The solvent and the coordination ability of the precursor zinc salt anion control the crystalline products formed by slow diffusion at room temperature: perchlorate allows isolation of the phase pure crystalline 1D polymer {[Zn(tph)(L)]·H₂O·3DMF}_n (1·H₂O·3DMF, DMF = N,N-dimethylformamide). In contrast, zinc chloride leads to the formation of either a mixture of polymeric 1·H₂O·3DMF and a dimeric molecular species [Zn₂Cl₂(tph)(L)₂]·4DMF (2·4DMF), or to the phase pure dimer 2·4DMF, depending on the Zn(ii) : tphH₂ stoichiometry. A modified synthesis using zinc nitrate and fast precipitation by base addition results in an amorphous analogue of the 1D polymer (3). Chains of 1·H₂O·3DMF pack into a non-porous crystalline material with a surface area of just 6 m² g^-1, while the outer surface area of amorphous polymer 3 is a factor of eight larger. Hence, the amorphous compound provides larger metal site accessibility for potential surface chemical reactions, while maintaining the coordination geometry of the metal sites. The temperature response of crystalline polymer 1·H₂O·3DMF was studied using multi-temperature single crystal X-ray diffraction (100-300 K). The a = b axes display normal positive thermal expansion, while the c axis remains constant with increasing temperature due to partial relaxation of the terephthalate linkers and slightly changed geometry within the individual polymer chains.

Semiconducting properties of pyridyl appended linear dicarboxylate based coordination polymers: theoretical prediction via DFT study

Coordination polymers (CPs) in recent times have emerged as active constituents in many semiconductor devices like light emitting diodes (LED), field effect transistors (FET), photovoltaic devices and Schottky barrier diodes. An intelligent choice of linkers, careful selection of metal ions and post synthetic modification (PSM) can provide a better pathway for charge transportation. However, a proper understanding of the charge transport mechanism in CPs is still inadequate due to the lack of considerable experimental and theoretical work. In this paper, we address the theoretical elucidation of semiconducting properties and a probable pathway for charge transportation in three of our previously published CPs using density functional theory (DFT). These results help us to recognize the orbitals that have major contributions in the formation of the valence band and also provide the most likely pathway for optimum electronic communication. In this regard, the role of hydrogen bonding and unpaired electrons of metal d-orbitals is also established.

A trinuclear Zn(ii) Schiff base azido compound: synthesis, structure and exploration of antimicrobial activity

The synthesis, characterization, X-ray crystal structure and antimicrobial activity of a trinuclear zinc(ii) complex have been explored.

One-pot crystallization of two 1,4-cyclohexanedicarboxylate-based tetranuclear Cu(ii) compounds and their DNA binding affinities

Two new tetranuclear Cu(ii) compounds have been synthesized using flexible linker 1,4-cyclohexanedicarboxylic acid in an one-pot crystallization which exhibit dissimilar affinities to DNA binding.

Exploration of semiconducting properties of Zn(ii)- and Cd(ii)-based coordination polymers with dicarboxylate of a chair-type backbone

This study highlights the comparison of electrical properties and device applications of d10 metal ion based coordination polymers.

Ultra-trace level detection of Cu2+ in an aqueous medium by novel Zn(ii)-dicarboxylato–pyridyl coordination polymers and cell imaging with HepG2 cells

Fluorescent 1D Zn(ii) coordination polymers are aggregated via noncovalent interactions. The emission of the CPs is exclusively quenched by Cu²⁺ and the LOD is at μM range. In aqueous medium internalization CPs within HepG2 cells is detected by microscopic cell image using Cu²⁺.

Electrically conductive 1D coordination polymers: design strategies and controlling factors

Due to the easy functionality and structural diversity of coordination polymers (CPs) coupled with superior thermal stability, many researchers have been prompted to explore the opportunity of introducing these hybrid materials as active components in various electronic devices, such as light emitting diodes (LED), solar cells, field effect transistors (FET), and Schottky barrier diodes (SBD). Therefore, the judicious selection of the structural components of CPs is directly related to their structure-property relationship and applications. One-dimensional (1D) CPs have recently emerged as excellent electrical conductors and are gaining enormous attention owing to their simple chain-like coordination arrays. In this article, we review the rational design strategies for synthesising 1D CPs and also point out the structural factors that affect the charge transport properties as well as the electrical conductivity of these materials.

Electrically conductive Cu(II)-based 1D coordination polymer with theoretical insight

A nitro-functionalized Cu(ii)-based one-dimensional coordination polymer (1D CP) [Cu(nip)(4-phpy)2]n (1) (H2nip = 5-nitroisophthalic acid and 4-phpy = 4-phenylpyridine) was synthesized and characterized by elemental analysis, powder X-ray diffraction (PXRD) and single crystal X-ray diffraction (SCXRD). In the solid-state self-assembly of 1, two sets of weak intermolecular forces, CHπ interaction among the axially bound 4-phpy ligands and ππ interaction among bridging nip ligands from adjacent 1D coordination polymeric chains led to 3D supramolecular packing. Interestingly compound 1 exhibited electrical conductivity in the semiconducting regime and behaved as a Schottky barrier diode.

(4′-Chloro-2,2′:6′,2′′-terpyridine-κ3 N,N′,N′′)bis(nitrato-κO)zinc(II)

The coordination of the Zn^II central atom in the title complex, [Zn(C₁₅H₁₀ClN₃)(NO₃)₂], exists in a distorted trigonal bipyramidal geometry defined by the nitro­gen atoms of the 4-chloro­terpyridine ligand and two monodentate nitrate groups.

In the title complex, [Zn(C₁₅H₁₀ClN₃)(NO₃)₂], the central zinc(II) atom is penta­coordinated by two O-bonded nitrate ions and three N atoms of the 4′-chloro-2,2′:6′,2′′-terpyridine ligand in a slightly distorted trigonal–bipyramidal shape. The main feature of the title complex packing is the presence of offset π–π inter­actions between the terpyridine rings in different layers. This structure constitutes the first known example of a zinc(II) 4-chloro­terpyridine complex with coordinating nitrate ions.

Chlorido(4′-chloro-2,2′:6′,2′′-terpyridine-κ3 N,N′,N′′)(trifluoromethanesulfonato-κO)zinc(II) acetonitrile monosolvate

The title compound structure is a unique example of a zinc(II) metal center surrounded by a tridentate chloro­terpyridine ligand, a chloride and a coordinated tri­fluoro­methane­sulfonate in a distorted square-pyramidal geometry.

In the title complex, [Zn(CF₃O₃S)Cl(C₁₅H₁₀ClN₃)]·CH₃CN, the zinc(II) core is fivefold coordinated by one chloride, one tri­fluoro­methane­sulfonate O atom and three terpyridine N atoms in a slightly distorted square-pyramidal geometry. The structure provides a distinct example amongst other zinc(II) 4-chloro­terpyridine complexes because of the unusual planarity of the coordinated chloride, the short length of the Zn—N bond opposite to the chloride ligand [1.9572 (15) Å], and the presence of an elongated Zn—O bond [2.3911 (14) Å] in the coordinated tri­fluoro­methane­sulfonate ion. A molecule of acetonitrile is also found in the asymmetric unit of the title complex.

Supramolecular assembly of a 4-(1-naphthylvinyl)pyridine-appended Zn(ii) coordination compound for the turn-on fluorescence sensing of trivalent metal ions (Fe3+, Al3+, and Cr3+) and cell imaging application

The as-synthesized Zn(ii) coordination compound exhibited turn-on fluorescence sensing of analytical group-IIIA metal ions (Fe³⁺, Al³⁺, and Cr³⁺) and applications in cell imaging.

Three-Dimensional-Coordination Polymer of Zn(II)-Carboxylate: Structural Elucidation, Photoelectrical Conductivity, and Biological Activity

A newly designed mixed-ligand coordination polymer [Zn₄(bdc)₄(ppmh)₂(H₂O)] _n (1) (H₂ bdc = 1,4-benzene dicarboxylic acid, ppmh = N-pyridin-2-yl-N'-pyridin-4-ylmethylene-hydrazine) has been characterized using different physicochemical techniques. The structure has been confirmed by single crystal X-ray diffraction measurements. There are two pyridyl-N and one hydrazino-imine-N donor centers in ppmh, where two pyridyl-Ns bind simultaneously to two Zn(II) to serve as a bridging agent to form a coordination polymer. The 1,4-benzene dicarboxylato (bdc) is ligated via the aromatic dicarboxylato-O to form a one-dimensional (1D) chain. These two 1D chains about Zn(II) constitute a two-dimensional structure, which undergoes noncovalent interactions (C-H···π and π···π) to generate a three-dimensional supramolecular assembly. Electrical conductivity of 1 is higher by 1 order (1.37 × 10^-6 S/cm) than that of the free ligand, ppmh (6.2 × 10^-7 S/cm). Especially, the responsivity of the compound 1 was 56.21 mA/W, which is 11 times higher than that of the ligand ppmh (5.12 mA/W). The specific detectivity of the compound was 2.17 × 10¹⁰ Jones, which is also almost 10 times higher with respect to the specific detectivity of the ligand-based device (4.53 × 10⁹ Jones). The results show that the compound can be valuable for optoelectronic fields. The biological studies suggest that compound 1 is antibacterial as well as a promising anticancer agent (LD₅₀, 42.2 μg/mL against HepG2 cells), while ligands remain silent. Investigation of the mechanism of the cell killing activity of compound 1 accounts the generation of intracellular reactive oxygen species.

Tuning of the para-position of pyridyl ligands impacts the electrical properties of a series of Cd(ii) ladder polymers

This work describes the tuning of electrical nature of three Cd(ii)-based 1D coordination polymers by the modifications of para-substituent of pyridyl ligands.

Two zinc(ii)-based coordination polymers with flexible dicarboxylate and pyridine mixed ligands: effect of π⋯π interactions on electrical activity

We synthesized two Zn(ii)-based 1D coordination polymers with paddle-wheel units using flexible 1,4-cyclohexanedicarboxylate linkers; these compounds exhibited electrical conductivity and Schottky barrier diode behavior.