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Synthesis, spectroscopic studies and DFT/TD-DFT/PCM calculations of molecular structure, spectroscopic characterization and NBO of charge transfer complex between 5-amino-1,3-dimethylpyrazole (5-ADMP) with chloranilic acid (CLA) in different solvents
摘要： New charge transfer complex between the n- and π-donor 5-amino-1,3-dimethyl pyrazole (5-ADMP) with the π-acceptor chloranilic acid was synthesized and characterized experimentally and theoretically. The experimental work was carried out in solution and solid state. The selected solvents were chloroform (CHL), methanol (MeOH), ethanol (EtOH) and acetonitrile (AN). upon mixing the donor with acceptor a change in color takes place immediately to pink one with absorption maxima at λmax 530, 531, 530 and 522 nm in CHL, EtOH, MeOH, and AN, respectively. The complex was stable for more than 2 h. The stability constant was calculated using Bensie-Hildebrand equation where it recorded the highest value in chloroform and the least one in methanol. Thermodynamic parameters were calculated where the enthalpy of formation recorded high value in chloroform. The solid complex was prepared where elemental analysis con?rmed its composition at 1:1 in concordant with that in solution. The infrared spectra of the formed complex con?rmed the existence of proton transfer hydrogen bond beside charge transfer interaction. A theoretical computations using DFT at the basis set B3LYP/6-31 G(d,p) was applied to support the experimental results. Optimization energy and geometrical parameters con?rmed the high stability of the complex due to the presence of CT beside PT in its chemical structure. Reactivity parameters strongly recommended that 5-ADMP is good electron donor and CLA is good electron acceptor. MEP maps con?rmed the presence of proton transfer hydrogen bond where OH of CLA is the electrophile and the pyridinic-like ring nitrogen of 5-ADMP is the nucleophile. The origin of electronic spectra was computed by TD-DFT using PCM as solvation model. Two absorption maxima were recorded in the calculated spectra attributing to π-π? and n-π? transitions in all media. Natural population analysis was applied to estimate the natural atomic charges and natural bond orbital (NBO). Both con?rmed the existence of strong proton transfer hydrogen bonding beside charge transfer in the produced complex.
关键词： DFT computations,Hydrogen bond,Pyrazole,Charge transfer,Spectroscopy
更新于2025-09-19 17:15:36
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The Role of Hydrogen-Bond Between Piperazine and Fullerene Molecules in Stabilizing Polymer:Fullerene Solar Cell Performance
摘要： Piperazine was recently reported as stabilizer for polymer:fullerene solar cells that can minimize the “burn-in” degradation of the cell. In this paper, the influence of N-substituents on the stabilization effect of piperazine in P3HT:PC61BM cells was investigated. Results confirmed that only piperazine derivatives (PZs) with N-H bond showed the stabilization effect, whereas the bis-alkyl substituted piperazine compounds do not able to improve the stability. Efficient photon-induced electron transfer (PET) process between PZ and PC61BM was only detected for the N-H containing PZ:PC61BM blends, corresponding ver well the stabilization effect of the PZs, which indicates that PET process of PZ and PC61BM stabilize the cell performance and the N-H bond plays a critical role ensuring the PET process and the consequent stabilization effect. Both 1H-NMR spectroscopy and theoretical calculation confirmed the formation of N-H…O-C and N-H…π bonds for the PC61BM-piperazine adduct, which was considered as the driving force that promotes the PET process between these two components. In addition, comparison of the calculated electron affinity energy (EA) and excitation energy (EEx) of PC61BM with/without piperazine confirmed that piperazine doping is able to promote the electron transfer (leads to the formation of PC61BM anions) than the energy transfer (leads to the formation of PC61BM excitons) between P3HT and PC61BM, which is beneficial for the performance and stability improvement.
关键词： Piperazine,Photochemistry,Degradation and Stability,Polymer Solar Cells,Hydrogen Bond
更新于2025-09-19 17:13:59
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Structures and Properties of Methylammonium Iodide Precursors of Halide Perovskites and Implications for Solar Cells: an Ab-Initio Investigation
摘要： Halide perovskite materials based on the prototypical CH3NH3PbI3 received much attention in recent years, with applications ranging from solar cells to light-emitting diodes. However, many fundamental aspects of the halide perovskite materials remain elusive at the moment, such as the structures and impacts of the methyl ammonium precursors on the halide perovskite properties. In this manuscript, we take one step back to theoretically investigate the monomer and dimer structures of methylammonium iodide, a precursor for the synthesis of the halide perovskite CH3NH3PbI3 via the first principles calculations, in order to provide a more complete view of the halide perovskite structures. The calculations show that the hydrogen bonds are found to be the major factor that stabilizes the methylammonium iodide monomers and dimers, while the dimeric structure exhibits geometry with each iodine atom shared by two neighbouring hydrogen atoms in the methylammonium cation molecules. The hydrogen bonds in the methylammonium iodide are proposed to be correlated with the three-dimensional halide perovskite buildup, and the formation of the hydrogen bond that is available in the halide perovskite framework could be “historically” traced back as early as the precursor preparation. The manuscript addresses the importance of the hydrogen bonds in the synthesis and the crystal formation of halide perovskite materials, and anticipates the necessity of the fundamental theoretical understanding of the structures from the halide perovskite precursors to the halide perovskite frameworks.
关键词： ab initio,perovskite solar cell,hydrogen bond,dimer,methylammonium iodide
更新于2025-09-19 17:13:59
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Efficient non-fullerene organic solar cells based on thickness-insensitive conjugated small molecule cathode interface
摘要： Interfacial engineering plays an essential role in the enhancement of device performance of organic solar cells (OSCs). Plentiful dopant-free electron- transporting materials have been e?ectively applied to modify ZnO in the inverted OSCs. However, these materials usually work with strict thickness, which observably limits their application in large area device fabrication. In this manuscript, an industrial small-molecule PyM with simply chemical structure solved in methyl alcohol was applied to modify ZnO in non-fullerene OSCs. PyM has good solubility in both methyl alcohol and chlorobenzene. Therefore, there is only a thin PyM layer left and distributed on the ZnO surface after coating the active layer. Meanwhile, a small amount PyM may be blended with the active layer near ZnO layer. The intense interaction between ZnO and PyM layer as well as the potential n-doping between PyM and the electron acceptor could modify the work function of ZnO and reduce the charge carrier recombination. Correspondingly, the inverted PBDB-T:ITIC OSCs with ZnO/PyM serving as electron transport layers achieve device power conversion e?ciency (PCE) of 10.9% and 10.0% with 10 nm and 105 nm thick PyM ?lm, respectively. The device performance is insensitive to the thickness of PyM. This phenomenon indicates that the PyM can be employed in roll-to-roll techniques to fabricate large-area devices at low cost. Similar results also emerged in PBDB-T:IT-M system, and the PCE was improved from 10.4% to 11.5% for ZnO and ZnO/PyM (~10 nm)-based devices.
关键词： Cathode interface,Organic solar cells,Hydrophobic property,Non-fullerene,Hydrogen bond,Thickness-insensitive
更新于2025-09-16 10:30:52
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[IEEE 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz2018) - Nagoya, Japan (2018.9.9-2018.9.14)] 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Studying Solvation by Non-linear THz Spectroscopy
摘要： We are using non-linear THz spectroscopy to study the ultrafast solvation dynamics of water. Hydrogen bond rearrangements via librational or diffusional motions constitute the heart of network dynamics in liquid water. Reorientation of water molecules on the ps and sub-ps time scale is a decisive step in the formation and breaking of hydrogen bonds. Here we report the results of ultrafast nonlinear THz experiments.
关键词： solvation dynamics,ultrafast dynamics,non-linear THz spectroscopy,hydrogen bond
更新于2025-09-10 09:29:36
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[Advances in Experimental Medicine and Biology] Glycobiophysics Volume 1104 || Synchrotron-Radiation Vacuum-Ultraviolet Circular-Dichroism Spectroscopy for Characterizing the Structure of Saccharides
摘要： Circular-dichroism (CD) spectroscopy is a powerful tool for analyzing the structures of chiral molecules and biomolecules. The development of CD instruments using synchrotron radiation has greatly expanded the utility of this method by extending the spectra to the vacuum-ultraviolet (VUV) region below 190 nm and thereby yielding information that is unobtainable by conventional CD instruments. This technique is especially advantageous for monitoring the structure of saccharides that contain hydroxy and acetal groups with high-energy transitions in the VUV region. Combining VUVCD spectra with theoretical calculations provides new insight into the contributions of anomeric hydroxy groups and rotational isomers of hydroxymethyl groups to the dynamics, intramolecular hydrogen bonds, and hydration of saccharides in aqueous solution.
关键词： Glycoprotein,Hydration,Circular dichroism,Synchrotron radiation,Time-dependent density functional theory,Molecular dynamics simulation,Saccharide,Intramolecular hydrogen bond,Solution structure,Structural dynamics,Vacuum ultraviolet,Glycosaminoglycan
更新于2025-09-10 09:29:36
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Investigation of hydrogen-bonding mediated molecular packing of diketopyrrolopyrrole based donor-acceptor oligomers in the solid state
摘要： Two diketopyrrolopyrrole (DPP)-based Donor-Acceptor oligomers with thermal labile 2-methylhexyl-2-oxylcarbonyl (mHoc) groups, mHocPBT and mHocTBT, were synthesized and characterized to study the hydrogen-bonding mediated molecular packing in solid state. The soluble oligomers can be converted to strong intermolecular hydrogen-bonded and pigment-like materials HPBT and HTBT by annealing the casted solid film at a temperature between 180 and 200 °C. The formation of intermolecular hydrogen bonding significantly altered the conformation of the molecules, molecular packing structure and related optical properties of the oligomers, with HPBT molecule exhibiting bathochromic shift and HTBT molecule exhibiting hypsochromic shift on UV/Vis spectra. Spin-casted mHocTBT and HTBT films also exhibited interesting morphology and charge transport properties. Even though the single mHocTBT oligomer molecule has a better coplanar molecular conformation as compared with that of HTBT, an enhanced π-π stacking structure and larger crystal grain size rendered HTBT film better charge transport performance.
关键词： Molecular Packing,Conjugated Molecules,Hydrogen Bond
更新于2025-09-10 09:29:36
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Insights into the excited state dynamical process for 3-hydroxy-2-(5-(5-(5-(3-hydroxy-4-oxo-4H-chromen-2-yl)thiophen-2-yl)thiophen-2-yl)thiophen-2-yl)-4H-chromen-4-one
摘要： In this present work, we theoretically investigate a novel system 3‐hydroxy‐2‐(5‐(5‐(5‐(3‐hydroxy‐4‐oxo‐4H‐chromen‐2‐yl)thiophen‐2‐yl)thiophen‐2‐yl)thiophen‐2‐yl)‐4H‐chromen‐4‐one (FT) based on density functional theory (DFT) and time‐dependent DFT (TDDFT) methods. Via calculating the reduced density gradient (RDG) versus sign(λ2) ρ, we firstly verify the formation of the dual intramolecular hydrogen bonds (O1─H2···O3 and O4─H5···O6) for FT form in the S0 state. Then comparing the primary structural parameters and corresponding infrared (IR) vibrational spectra involved in hydrogen bonds between S0 and S1 state, we demonstrate that these two intramolecular hydrogen bonds should be strengthened in the S1 state. Insights into the vertical excitation process, our theoretical results reproduced experimental absorption nature, which confirms that the theoretical level (B3LYP/TZVP) is reasonable and effective in this work. And frontier molecular orbitals (MOs) depict the nature of electronically excited state and support the excited‐state intramolecular proton transfer (ESIPT) reaction. According to the calculated results of potential energy curves along stepwise and synergetic O1─H2 and O4─H5 coordinates, we verify that only the excited‐state single‐proton transfer could occur for FT molecule in the S1 state, although it possesses two intramolecular hydrogen bonds. We not only investigate the detail excited‐state behaviors for FT system and elaborate the ESIPT mechanism but also explain previous experimental results.
关键词： charge redistribution,ESIPT,intramolecular hydrogen bond,charge density difference
更新于2025-09-04 15:30:14
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Evaluation of Exfoliated Graphite to Graphene in Polyamide 66 Using Novel High Shear Elongational Flow
摘要： Graphene has been publicized as the game changing material of this millennium. To this day, scalable production leading to exceptional material properties has been difficult to attain. Most methods require harsh chemicals, which result in destroying the graphene surface. A method was developed, exploiting high speed elongational flow in a novel designed batch mixer; creating a distribution of pristine few to many layer graphene flakes. The method focuses on exfoliating in a molten polyamide 66 (PA66) matrix, creating a graphene reinforced polymer matrix composite (G-PMC). The process revealed that high speed elongational flow was able to create few layer graphene. Graphite exfoliation was found driven in part by diffusion, leading to intercalation of PA66 in graphite. The intercalated structure lead to increases in the hydrogen bonding domain, creating anisotropic crystal domains. The thermal stability of the G-PMC was found to be dependent to the degree of exfoliation, PA66 crystal structure and composite morphology. The aim of this research is to characterize uniquely produced graphene containing polymer matrix composites using a newly created elongational flow field. Using elongational flow, graphite will be directly exfoliated into graphene within a molten polymer.
关键词： polyamide 66,elongational flow,graphene polymer matrix composite,hydrogen bond,graphene
更新于2025-09-04 15:30:14