PubMed İndeksli Yayınlar Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12573/397
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Article Citation - WoS: 19Citation - Scopus: 19Understanding and Tailoring Excited State Properties in Solution-Processable Oligo(p-Phenyleneethynylene)s: Highly Fluorescent Hybridized Local and Charge Transfer Character via Experiment and Theory(Amer Chemical Soc, 2021-10-13) Usta, Hakan; Cosut, Bunyemin; Alkan, FahriRod-shaped oligo(p-phenyleneethynylene) (OPE) offers an attractive p-framework for the development of solution-processable highly fluorescent molecules having tunable hybridized local and charge transfer (HLCT) excited states and (reverse) intersystem crossing ((R)ISC) channels. Herein, an HLCT oligo(p-phenyleneethynylene) library was studied for the first time in the literature in detail systematically via experiment and theory. The design, synthesis, and full characterization of a new highly fluorescent (Phi(PL-solution) similar to 1) sky blue emissive 4',4 ''-((2,5-bis((2-ethylhexyl)oxy)-1,4-phenylene)bis(ethyne-2,1-diyl))bis(N,N-diphenyl-[1,1'-bi-phenyl]-4-amine) (2EHO-TPA-PE) was also reported. The new molecule consists of a D'-Ar-pi-D-pi-Ar-D' molecular architecture with an extended pi-spacer and no acceptor unit, and detailed structural, physicochemical, single-crystal, and optoelectronic characterizations were performed. A high solid-state quantum efficiency (Phi(PL-solution) similar to 0.8) was achieved as a result of suppressed exciton-phonon/vibronic couplings (no pi-pi interactions and multiple (14 per dimeric form) strong C-H center dot center dot center dot pi interactions). Strong solution-phase/solid-state dipole-dependent tunable excited state behavior (local excited (LE) -> HLCT -> charge transfer (CT)) and decay dynamics covering a wide spectral region were demonstrated, and the CT state was observed to be highly fluorescent despite extremely large Stokes shift (similar to 130 nm)/fwhm (similar to 125 nm) and significant charge separation (0.75 charge.nm). Employing the Lippert-Mataga model, along with detailed photophysical studies and TDDFT calculations, key relationships between molecular design-electronic structure-exciton characteristics were elucidated with regards to HLCT and hot exciton channel formations. The interstate coupling between CT and LE states and the interplay of this coupling with respect to medium polarity were explored. A key relationship between excited-state symmetry breaking process and the formation of HLCT state was discussed for TPA-ended rod-shaped OPE p-systems. (R)ISC-related delayed fluorescence (tau similar to 2-6 ns) processes were evident following the prompt decays (similar to 0.4-0.9 ns) both in the solution and in the solid-state. As a unique observation, the delayed fluorescence could be tuned and facilitated via small dielectric changes in the medium. Our results and the molecular engineering perspectives presented in this study may provide unique insights into the structural and electronic factors governing tunable excited state and hot-exciton channel formations in OPEs for (un)conventional solution-processed luminescence applications.Article Citation - WoS: 13Citation - Scopus: 13Tuning the Shades of Red Emission in InP/ZnSe Nanocrystals With Narrow Full Width for Fabrication of Light-Emitting Diodes(Amer Chemical Soc, 2023-10-13) Soheyli, Ehsan; Bicer, Aysenur; Ozel, Sultan Suleyman; Tiras, Kevser Sahin; Mutlugun, Evren; Sahin Tiras, KevserWhile Cd-based luminescent nanocrystals (NCs) are the most mature NCs for fabricating efficient red light-emitting diodes (LEDs), their toxicity related limitation is inevitable, making it necessary to find a promising alternative. From this point of view, multishell-coated, red-emissive InP-based NCs are excellent luminescent nanomaterials for use as an emissive layer in electroluminescent (EL) devices. However, due to the presence of oxidation states, they suffer from a wide emission spectrum, which limits their performance. This study uses tris-(dimethyl-amino)-phosphine (3DMA-P) as a low-cost aminophosphine precursor and a double HF treatment to suggest an upscaled, cost-effective, and one-pot hot-injection synthesis of purely red-emissive InP-based NCs. The InP core structures were coated with thick layers of ZnSe and ZnS shells to prevent charge delocalization and to create a narrow size distribution. The purified NCs showed an intense emission signal as narrow as 43 nm across the entire red wavelength range (626-670 nm) with an emission quantum efficiency of 74% at 632 nm. The purified samples also showed an emission quantum efficiency of 60% for far-red wavelengths of 670 nm with a narrow full width of 50 nm. The samples showed a relatively long average emission lifetime of 50-70 ns with a biexponential decay profile. To demonstrate the practical ability of the prepared NCs in optoelectronics, we fabricated a red-emissive InP-based LEDs. The best-performing device showed an external quantum efficiency (EQE) of 1.16%, a luminance of 1039 cd m(-2), and a current efficiency of 0.88 cd A(-1).Article Citation - WoS: 6Citation - Scopus: 7Tailored Synthesis of Iron Oxide Nanocrystals for Formation of Cuboid Mesocrystals(Amer Chemical Soc, 2021-08-02) Soran-Erdem, Zeliha; Sharma, Vijay Kumar; Hernandez-Martinez, Pedro Ludwig; Demir, Hilmi VolkanIn this work, we systematically studied the shape- and size-controlled monodisperse synthesis of iron oxide nanocrystals (IONCs) for their use as building blocks in the formation of mesocrystals. For this aim, on understanding the influence of the oleic acid concentration, iron-oleate concentration, and heating rate on the synthesis of robust and reproducible IONCs with desired sizes and shapes, we synthesized highly monodisperse similar to 11 nm sized nanocubes and nanospheres. Magnetic measurements of both cubic and spherical IONCs revealed the presence of mixed paramagnetic and superparamagnetic phases in these nanocrystals. Moreover, we observed that the magnetic moments of the nanocubes are more substantial compared to their spherical counterparts. We then demonstrated a simple magnetic-field-assisted assembly of nanocubes into three-dimensional (3D) cuboid mesocrystals while nanospheres did not form any mesocrystals. These findings indicate that small cubic nanocrystals hold great promise as potential building blocks of 3D magnetic hierarchical structures with their superior magnetic properties and mesocrystal assembly capability, which may have high relevance in various fields ranging from high-density data storage to biomedical applications.Article Citation - WoS: 11Citation - Scopus: 13Solution-Processable Indenofluorenes on Polymer Brush Interlayer: Remarkable N-Channel Field-Effect Transistor Characteristics Under Ambient Conditions(Amer Chemical Soc, 2023-08-15) Can, Ayse; Deneme, Ibrahim; Demirel, Gokhan; Usta, HakanThe development of solution-processable n-type molecularsemiconductorsthat exhibit high electron mobility (& mu;(e) & GE;0.5 cm(2)/(V & BULL;s)) under ambient conditions, along withhigh current modulation (I (on)/I (off) & GE; 10(6)-10(7)) andnear-zero turn on voltage (V (on)) characteristics,has lagged behind that of other semiconductors in organic field-effecttransistors (OFETs). Here, we report the design, synthesis, physicochemicaland optoelectronic characterizations, and OFET performances of a libraryof solution-processable, low-LUMO (-4.20 eV) 2,2 & PRIME;-(2,8-bis(3-alkylthiophen-2-yl)indeno[1,2-b]fluorene-6,12-diylidene)dimalononitrile small molecules, & beta;,& beta;& PRIME;-C (n) -TIFDMTs, having varied alkyl chain lengths (n = 8, 12, 16). An intriguing correlation is identifiedbetween the solid-isotropic liquid transition enthalpies andthe solubilities, indicating that cohesive energetics, which are tunedby alkyl chains, play a pivotal role in determining solubility. Thesemiconductors were spin-coated under ambient conditions on denselypacked (grafting densities of 0.19-0.45 chains/nm(2)) ultrathin (& SIM;3.6-6.6 nm) polystyrene-brush surfaces.It is demonstrated that, on this polymer interlayer, thermally induceddispersive interactions occurring over a large number of methyleneunits between flexible alkyl chains (i.e., zipper effect) are criticalto achieve a favorable thin-film crystallization with a proper microstructureand morphology for efficient charge transport. While C-8 and C-16 chains show a minimal zipper effect upon thermalannealing, C-12 chains undergo an extended interdigitationinvolving & SIM;6 methylene units. This results in the formationof large crystallites having lamellar stacking ((100) coherence length & SIM;30 nm) in the out-of-plane direction and highly favorablein-plane & pi;-interactions in a slipped-stacked arrangement. Uninterruptedmicrostructural integrity (i.e., no face-on (010)-oriented crystallites)was found to be critical to achieving high mobilities. The excellentcrystallinity of the C-12-substituted semiconductor thinfilm was also evident in the observed crystal lattice vibrations (phonons)at 58 cm(-1) in low-frequency Raman scattering. Two-dimensionalmicrometer-sized (& SIM;1-3 & mu;m), sharp-edged plate-likegrains lying parallel with the substrate plane were observed. OFETsfabricated by the current small molecules showed excellent n-channelbehavior in ambient with & mu;(e) values reaching & SIM;0.9cm(2)/(V & BULL;s), I (on)/I (off) & SIM; 10(7)-10(8), and V (on) & AP; 0 V. Our study notonly demonstrates one of the highest performing n-channel OFET devicesreported under ambient conditions via solution processing but alsoelucidates significant relationships among chemical structures, molecularproperties, self-assembly from solution into a thin film, and semiconductingthin-film properties. The design rationales presented herein may openup new avenues for the development of high-electron-mobility novelelectron-deficient indenofluorene and short-axis substituted donor-acceptor & pi;-architectures via alkyl chain engineering and interface engineering.Article Citation - WoS: 25Citation - Scopus: 25Self-Resonant Microlasers of Colloidal Quantum Wells Constructed by Direct Deep Patterning(Amer Chemical Soc, 2021-05-24) Gheshlaghi, Negar; Foroutan-Barenji, Sina; Erdem, Onur; Altintas, Yemliha; Shabani, Farzan; Humayun, Muhammad Hamza; Demir, Hilmi VolkanHere, the first account of self-resonant fully colloidal mu-lasers made from colloidal quantum well (CQW) solution is reported. A deep patterning technique is developed to fabricate well-defined high aspect-ratio on-chip CQW resonators made of grating waveguides and in-plane reflectors. The fabricated waveguide-coupled laser, enabling tight optical confinement, assures in-plane lasing. CQWs of the patterned layers are closed-packed with sharp edges and residual-free lifted-off surfaces. Additionally, the method is successfully applied to various nanoparticles including colloidal quantum dots and metal nanoparticles. It is observed that the patterning process does not affect the nanocrystals (NCs) immobilized in the attained patterns and the different physical and chemical properties of the NCs remain pristine. Thanks to the deep patterning capability of the proposed method, patterns of NCs with subwavelength lateral feature sizes and micron-scale heights can possibly be fabricated in high aspect ratios.Article Citation - WoS: 27Citation - Scopus: 29Revisiting the Role of Charge Transfer in the Emission Properties of Carborane-Fluorophore Systems: A TDDFT Investigation(Amer Chemical Soc, 2022-06-05) Tahaoglu, Duygu; Usta, Hakan; Alkan, FahriIn this study, we performed a detailed investigation of the S-1 potential energy surface (PES) of o-carborane-anthracene (o-CB-Ant) with respect to the C-C bond length on o-CB and the dihedral angle between o-CB and Ant moieties. The effects of different substituents (F, Cl, CN, and OH) on carbon- or boron-substituted o-CB, along with a pi-extended acene-based fluorophore, pentacene, on the nature and energetics of S-1 -> S-0 transitions are evaluated. Our results show the presence of a non-emissive S-1 state with an almost pure charge transfer (CT) character for all systems as a result of significant C-C bond elongation (C-C = 2.50-2.56 angstrom) on o-CB. In the case of unsubstituted o-CB-Ant, the adiabatic energy of this CT state corresponds to the global minimum on the S-1 PES, which suggests that the CT state could be involved in emission quenching. Despite large deformations on the o-CB geometry, predicted energy barriers are quite reasonable (0.3-0.4 eV), and the C-C bond elongation can even occur without a noticeable energy penalty for certain conformations. With substitution, it is shown that the dark CT state becomes even more energetically favorable when the substituent shows -M effects (e.g., -CN), whereas substituents showing +M effects (e.g., -OH) can result in an energy increase for the CT state, especially for partially stretched C-C bond lengths. It is also shown that the relative energy of the CT state on the PES depends strongly on the LUMO level of the fluorophore as this state is found to be energetically less favorable compared to other conformations when anthracene is replaced with pi-extended pentacene. To our knowledge, this study shows a unique example of a detailed theoretical analysis on the PES of the S-1 state in o-CB-fluorophore systems with respect to substituents or fluorophore energy levels. Our findings could guide future experimental work in emissive o-CB-fluorophore systems and their sensing/optoelectronic applications.Article Citation - WoS: 22Citation - Scopus: 24Nanoclay- and TiO2 Nanoparticle-Modified Poly(n-Vinyl Pyrrolidone) Hydrogels: A Multifunctional Material for Application in Photocatalytic Degradation and Adsorption-Based Removal of Organic Contaminants(Amer Chemical Soc, 2022-09-22) Marouch, Salsabil; Benbellat, Noura; Duran, Ali; Yilmaz, ErkanIn recent times, access to clean water has become increasingly difficult and one of the most important problems for the sustainability of life due to environmental pollution. Based on this thought, in this study, a multifunctional hydrogel nanocomposite (nanoclay@TiO2@PNVP) containing linear poly(N-vinyl pyrrolidone) (PNVP), nanoclay, and TiO2 nanoparticles was synthesized and used as an adsorbent and photocatalyst for the adsorption-based and photocatalytic degradation-based removal of organic and pharmaceutical pollutants such as methylene blue (MB) and sildenafil citrate (SLD). The modification of the hydrogel with TiO2 nanoparticles and nanoclay aimed to increase the adsorption capacity of the PNVP hydrogel as well as to gain photocatalytic properties for the effective removal of organic contaminants. This hybrid material, which can be cleaned in two different ways, can be reused and recycled at least 10 times. Characterization studies were carried out using Fourier transform infrared spectroscopy, scanning electron microscopy, Raman spectroscopy, thermogravimetric analysis, differential thermogravimetry, and viscosimetry techniques. Optimization studies for the adsorption-based removal of organic contaminants were carried out on MB and SLD as model organic compounds. The optimum parameters for MB were found at pH 10 of the sample solution when 50 mg of the nanoclay@TiO2@PNVP hydrogel nanocomposite was used for 420 min of contact time. It was observed that 99% of the MB was photocatalytically degraded within 150 min at pH 10. Our material had multifunctional applicability properties, showing high adsorption and photocatalytic performances over 99% for at least 10 times of use. For the removal of organic and pharmaceutical contaminants from wastewater, the synthesized material can be used in two treatment processes separately or in combination in one step, providing an important advantage for its usability in environmental applications.Article Citation - WoS: 51Citation - Scopus: 56Machine Learning-Aided Inverse Design and Discovery of Novel Polymeric Materials for Membrane Separation(Amer Chemical Soc, 2024-12-16) Dangayach, Raghav; Jeong, Nohyeong; Demirel, Elif; Uzal, Nigmet; Fung, Victor; Chen, YongshengPolymeric membranes have been widely used for liquid and gas separation in various industrial applications over the past few decades because of their exceptional versatility and high tunability. Traditional trial-and-error methods for material synthesis are inadequate to meet the growing demands for high-performance membranes. Machine learning (ML) has demonstrated huge potential to accelerate design and discovery of membrane materials. In this review, we cover strengths and weaknesses of the traditional methods, followed by a discussion on the emergence of ML for developing advanced polymeric membranes. We describe methodologies for data collection, data preparation, the commonly used ML models, and the explainable artificial intelligence (XAI) tools implemented in membrane research. Furthermore, we explain the experimental and computational validation steps to verify the results provided by these ML models. Subsequently, we showcase successful case studies of polymeric membranes and emphasize inverse design methodology within a ML-driven structured framework. Finally, we conclude by highlighting the recent progress, challenges, and future research directions to advance ML research for next generation polymeric membranes. With this review, we aim to provide a comprehensive guideline to researchers, scientists, and engineers assisting in the implementation of ML to membrane research and to accelerate the membrane design and material discovery process.Article Citation - WoS: 35Citation - Scopus: 36In Situ Synthesis of Horseradish Peroxidase Nanoflower@Carbon Nanotube Hybrid Nanobiocatalysts With Greatly Enhanced Catalytic Activity(Amer Chemical Soc, 2023-03-21) Dadi, Seyma; Temur, Nimet; Gul, O. Tolga; Yilmaz, Vedat; Ocsoy, IsmailOrganic-inorganic hybrid nanoflowers (NFs) consisting of horseradish peroxidase (HRP) and copper II (Cu2+) are successfully synthesized with the involvement of carbon nanotubes (CNTs) by in situ and post-modification methods. Catalytic activities of in situ synthesized HRP-NF@CNT (HRP-NF@CNT-Is) and post-modification-synthesized HRP-NF@CNTs (HRP-NF@CNT-Pm) are systematically examined. The 30 mg CNTs incorporated HRP-NF@CNT-Is (HRP-NF@ CNT-30Is) exhibits greatly increased catalytic activity and stability toward 3,3 ',5,5 '-tetramethylbenzidine (TMB), thanks to the synergistic effect between HRP-NF and CNTs and the peroxidase-like activity of CNTs in the presence of hydrogen peroxide (H2O2). While HRP-NF@CNT-30Is retains almost 85% of its initial activity even after 10 cycles, HRP-NF (without CNTs) loses half of its initial activity at the same experimental conditions. We study how two experimental parameters, the pH values and temperatures, influence the catalytic activity of HRP-NF@CNT-30Is, in addition to the fact that HRP-NF@CNT-30Is is employed to detect the presence of H2O2 and glutathione (GSH) with colorimetric and spectrophotometric readouts. For instance, HRP-NF@CNT-30Is is used to sensitively detect H2O2 in the range of 20 to 300 mu M with an LOD of 2.26 mu M. The catalytic activity of HRP-NF@CNT-30Is is suppressed in the presence of GSH, and then an obvious color change from blue to nearly colorless is observed. Using this strategy, GSH is also sensitively determined in the range of 20-200 mu M with an LOD of 11.2 mu M. We expect that HRP-NF@CNTs can be used as a promising and novel nanobiocatalyst for various biomedical and industrial applications in the near future.Article Citation - WoS: 6Citation - Scopus: 8Histone Deacetylase Inhibition and Autophagy Modulation Induces a Synergistic Antiproliferative Effect and Cell Death in Cholangiocarcinoma Cells(Amer Chemical Soc, 2023-06-08) Yenigul, Munevver; Akcok, Emel Basak Gencer; Gencer Akçok, Emel BaşakCholangiocarcinoma, also known as biliary tract cancer,is an aggressiveadenocarcinoma arising from epithelial cells lining the intra- andextrahepatic biliary system. The effects of autophagy modulators andhistone deacetylase (HDAC) inhibitors in cholangiocarcinoma are notfully known. It is essential to understand the molecular mechanismsand the effects of HDAC inhibitors in the context of cholangiocarcinoma.The antiproliferative effect of different HDAC inhibitors and autophagymodulation was investigated by the MTT cell viability assay in TFK-1and EGI-1 cholangiocarcinoma cell lines. Combination indexes werecalculated using CompuSyn software. Consequently, apoptosis was detectedby Annexin V/PI staining. The effect of the drugs on the cell cyclewas measured by the propidium iodide staining. The HDAC inhibitionwas confirmed via acetylated histone protein levels by western blotting.HDAC inhibitors, MS-275 and romidepsin, showed a better synergisticeffect with the nocodazole combination. The combination treatmentexerted its growth inhibitory effect by cell cycle arrest and inductionof apoptosis. The cell cycle analysis of the combination treatmentshowed that the S phase and G2/M phase were achieved. Moreover, thenecrotic and apoptotic cell population increased after single HDACinhibitors and combination treatment. The anti-cancer effect of HDACinhibitors is revealed by acetylation levels of histones. While acetylationlevels were increased in response to HDAC inhibitors and autophagymodulator combinations, the HDAC expression decreased. This studyhighlights the importance of the combination of HDAC inhibition andautophagy modulators and demonstrates a synergistic effect, whichcould be a promising therapy and novel treatment approach for cholangiocarcinoma.