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This article studies the synthesis, as well as the structural, vibrational, and optical properties of Eu 3+ -doped ZnO quantum dots (QDs) and investigates the energy transfer mechanism from the ZnO host to Eu 3+ ions using Reisfeld's approximation. Eu 3+ -doped ZnO QDs at varying concentrations (0-7%) were successfully prepared using a wet chemical method. The successful doping of Eu 3+ ions into the ZnO host lattice, as well as the composition and valence states of the elements present in the sample, were confirmed through X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses. XRD results demonstrated the crystalline nature of the ZnO QDs, revealing their wurtzite (WZ) structure with no secondary phases. XPS analysis provided further confirmation of the presence of Eu 3+ ions within the ZnO host, with clear signals corresponding to the Zn, O, and Eu elements. The valence states of Eu were verified as trivalent (Eu 3+ ), confirming the successful doping of Eu 3+ ions, as evidenced by the characteristic Eu 3d peaks in the XPS spectra. Raman spectroscopy (RS) was employed to analyze the vibrational modes, revealing shifts in ZnO lattice vibrations due to Eu 3+ incorporation, indicating strong coupling between Eu 3+ ions and the ZnO host. Optical properties were studied using UV-Vis absorption, photoluminescence (PL) spectroscopy, and PL decay spectroscopy, showing a significant enhancement of red emission, attributed to the 5 D 0 → 7 F 2 transition of Eu 3+ ions under UV excitation. Using Judd-Ofelt (JO) analysis, the intensity parameters ( Ω 2 , Ω 4 , Ω 6 ) were derived, providing insights into the asymmetry of the Eu 3+ ion's local environment and the radiative transition probabilities. Energy transfer processes between the ZnO host and Eu 3+ dopants were examined, showing efficient sensitization of Eu 3+ through excitation of the ZnO host, with an optimal Eu 3+ doping level maximizing luminescence. Eu 3+ -doped ZnO QDs, which emit in the visible light region and are non-toxic, have great potential for applications in photonic devices, light-emitting diodes, and bioimaging., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

CdSe quantum dots (QDs) with size in the range of 3.5-5.8 nm and a zinc blende (ZB) crystal structure were synthesized by the wet chemical method. The morphology of the synthesized QDs was assessed by transmission electron microscopy (TEM). The structural and optical properties were characterized by X-ray diffraction (XRD), absorption spectroscopy (Abs) and photoluminescence (PL) spectroscopy. The anti-cancer activity of CdSe QDs was investigated on AGS gastric cancer cells through cell viability screening (MTT assay), cell cycle and apoptosis analysis using flow cytometry. The generation of reactive oxygen species (ROS) was analyzed using the cell fluorescence staining method with H2DCFDA. Three QD series of CdSe1 (3.5 nm), CdSe2 (4.7 nm) and CdSe3 (5.8 nm) have been selected to study their effects on the extermination of stomach cancer cells. The CdSe QDs all exhibited the potential to induce toxicity to cells at concentrations ranging from 5 to 20 μg mL -1 . CdSe2 demonstrated a significant impact on cell proliferation compared to the CdSe1 and CdSe3 forms ( p < 0.01). CdSe QDs caused cell cycle arrest, leading to the accumulation of cells in the G0/G1 phase, while also increasing the rate of apoptosis compared to the control ( p < 0.01). More importantly, it has been demonstrated that CdSe QDs promote excessive production of ROS in AGS cells, which is believed to be the cause of apoptosis and the reduction of cell proliferation. These data suggest that CdSe QDs are a good candidate for combating gastric cancer cells., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

In this study, Eu 3+ ion singly doped and Eu 3+ /Sm 3+ ions co-doped ZnS semiconductor quantum dots (QDs) were successfully synthesized using a wet chemical method in 1-octadecene (ODE) solvent. The successful doping of Sm 3+ and Eu 3+ ions into the ZnS host lattice and the composition and valence of the elements present in the sample were confirmed by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Structural and morphological studies revealed the presence of Eu 3+ -doped ZnS and Eu 3+ /Sm 3+ co-doped ZnS QDs of about 3-4 nm size with a zinc blende structure. The Judd-Ofelt (J-O) intensity parameters of Eu 3+ -doped ZnS QDs were determined from their fluorescence spectra. The optical properties of Eu 3+ /Sm 3+ co-doped ZnS QDs were studied by changing the Eu 3+ ion concentration and fixing the Sm 3+ ion concentration. The photoluminescence (PL) spectra of Eu 3+ /Sm 3+ co-doped ZnS QDs were obtained at an excitation wavelength of 403 nm ( 6 H 5/2 → 6 P 3/2 transition of Sm 3+ ions) in the 525-725 nm range. The effective energy transfer (ET) process from Sm 3+ to Eu 3+ ions was confirmed and explained in detail using the Reisfeld approximation and the Inokuti-Hirayama model. The CIE color coordinates of the Eu 3+ /Sm 3+ co-doped ZnS QDs were obtained using PL spectral data. Eu 3+ /Sm 3+ co-doped ZnS QDs exhibited a long lifetime and emitted warm red light. These interesting properties give Eu 3+ /Sm 3+ co-doped ZnS QDs great potential for applications in photovoltaics, photocatalysis, and biomarkers.

CoAl 2 O 4 : x Dy 3+ nanocrystals ( x = 0, 0.1, 0.5, 1.0, and 3.0 mol%) with spinel structures were prepared using the co-precipitation method. The crystal structure, optical properties, and presence of elements were respectively analyzed using X-ray diffraction, photoluminescence excitation, photoluminescence spectra, luminescence lifetime, and X-ray photoelectron spectroscopy. The influence of temperature on material fabrication was studied using differential scanning calorimetry and thermogravimetric techniques. The color characteristics of Dy 3+ luminescence in the CoAl 2 O 4 host were evaluated using CIE chromaticity coordinates and correlated color temperature. For the first time, the electronic dipole transitions in the photoluminescence excitation spectra were used to calculate the optical parameters of Dy 3+ ions in the CoAl 2 O 4 host using Judd-Ofelt theory. The Inokuti-Hirayama model was used to explain the energy transfer process between Dy 3+ ions, the main interaction mechanism, and energy transfer parameters for the luminescence of Dy 3+ ions., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

In this study, Er-doped CoAl 2 O 4 nanocrystals (NCs) were synthesized via co-precipitation. All the NCs were crystallized in the form of a single phase with a spinel structure and Er 3+ ions replaced Al 3+ ions in the formation of the CoAl 2- x Er x O 4 alloy structure. The optical characteristics of the Er 3+ ion-doped CoAl 2 O 4 NCs were thoroughly investigated by analyzing both the UV-VIS and photoluminescence spectra, using the Judd-Ofelt theory. The effect of Er doping content on the luminescent properties of the CoAl 2 O 4 pigment (using lasers emitting at wavelengths of 413 and 978 nm) has been studied. The values of Judd-Oflet intensity parameters ( Ω 2 , Ω 4 , and Ω 6 ) were determined from the absorption spectra using the least square fitting method. The J-O parameters were calculated and compared with those of other host materials; the values of the Ω 2 , Ω 4 , and Ω 6 parameters decreased with an increase in Er concentration. This suggests that the rigidity and local symmetry of the host materials become weaker as the concentration of Er 3+ ions increases. The highest value of the Ω 2 parameter, when compared with Ω 4 and Ω 6 , suggests that the vibrational frequencies in the given samples are relatively low. The upconversion fluorescence phenomenon was observed and explained in detail under an excitation wavelength of 978 nm when the excitation power was varied., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

In this study, CdTe x Se 1- x (0 ≤ x ≤ 1) and CdTeSe:Gd y % ( y = 0-8.05) alloy semiconductor nanocrystals (NCs) were prepared by wet chemical method. The presence and composition of the elements in the sample were determined by energy dispersive X-ray (EDX) spectroscopy and X-ray photoelectron spectroscopy (XPS). Structural analysis of X-ray diffraction (XRD) patterns indicated that most NCs crystallized in the zinc blende (ZB) structure however some Gd-doped NCs ( y = 4.52 and 8.05%) crystallized in the wurtzite (WZ) structure. The emission peak of CdTe x Se 1- x (0 ≤ x ≤ 1) NCs varied over a wide range when changing x while the particle size remained almost unchanged. The effect of Gd doping on the structure and optical and magnetic properties of CdTeSe NCs was studied in detail. When the Gd concentration increases from 0-8.05%: (i) the structure of CdTeSe NCs gradually changed from ZB to WZ, (ii) the emission efficiency of the material was significantly reduced, (iii) the PL lifetime of samples increased more than 10 times, and (iv) the ferromagnetic properties of the material were enhanced. The research findings demonstrated that it is possible to control the crystal structure, optical characteristics, and magnetic properties of Gd-doped CdTeSe nanocrystals by adjusting the dopant concentration and chemical composition of the host material., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

After conducting an in silico analysis of the cryptic mdk cluster region and performing transcriptomic studies, an integrative Streptomyces BAC Vector containing the mdk gene sequence was constructed. The heterologous expression of the mdk cluster in Streptomyces albus J1074 resulted in the production of the angucyclic product, seongomycin, which allowed for the assesment of its antibacterial, antiproliferative, and antiviral activities. Heterologous production was further confirmed by targeted knock-out experiments involving key regulators of the biosynthetic pathways. We were further able to revise the core structure of maduralactomycin A, using a computational approach., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

In this study, Er 3+ doped ZnO semiconductor quantum dots (QDs) were synthesized using a wet chemical method. The successful doping of Er 3+ ions into the ZnO host lattice and the elemental composition was confirmed by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The ZnO and Er 3+ doped ZnO QDs with a hexagonal structure, spherical shape, and particle size of approximately 5 nm were revealed by XRD and transmission electron microscopy (TEM). The absorption, luminescence properties, and fluorescence lifetimes of the samples were studied as the concentration of Er 3+ ions varied. The intensity parameters, emission transition probabilities, branching ratios, and emission lifetimes of the excited levels of Er 3+ ions in the ZnO host were determined using the Judd-Ofelt theory, which provided insight into the covalent relationship between the ions and ligands as well as the nature of the ZnO host lattice. Moreover, the energy transfer process from the ZnO host to Er 3+ ions and the yield of this process are explained in detail along with specific calculations. The Er 3+ doped ZnO QDs displayed a significantly longer lifetime than undoped ZnO, which opens up many potential applications in fields such as photocatalysis, optoelectronics, photovoltaics, and biosensing., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Tb3+-Doped ZnSe quantum dots (QDs) with a Tb content in the range of 0.5-7% were successfully synthesized by a wet chemical method. X-Ray diffraction (XRD) and transmission electron microscopy (TEM) analyses revealed that the as-synthesized QDs had a zinc blende (ZB) structure with a particle size of approximately 4 nm. The effect of Tb-doping on the structure and optical properties of the ZnSe QDs was studied. The emission spectra and photoluminescence (PL) decay kinetics data confirmed the successful incorporation of Tb3+ ions into the ZnSe host. The PL spectra also revealed that the intensity of dopant emission was significantly enhanced owing to the energy transfer (ET) from the host emission. The efficiency of the ET process from the ZnSe host to Tb3+ ions and between Tb3+ ions and the nature of these interaction mechanisms were determined by applying the Inokuti-Hirayama and Reisfeld models. The features of the ligand field and the optical properties of Tb3+ ions in the ZnSe QDs were studied using Judd-Ofelt theory. The dependence of the chromaticity features of ZnSe:Tb3+ QDs on the Tb concentration was estimated by the chromaticity coordinates and correlated color temperature (CCT). The Tb3+-doped ZnSe QDs with visible, tunable, and very long lifetime emission have potential for practical applications such as biological labeling, photocatalysis, and white-LED devices.

The role of samarium (Sm) dopant on the structural, morphological, and optical properties of CdS QDs and CdS/ZnS core/shell QDs was methodically reported. The synthesis of Sm-doped CdS QDs and CdS/ZnS QDs was carried out via a facile wet chemical method. The structure, chemical composition, and optical properties of the synthesized QDs were investigated by using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy (RS), and photoluminescence (PL) spectroscopy. XRD analysis showed that the synthesized CdS QDs exhibited zinc blende structure which was not affected by doping Sm 3+ ions. The particle size of the CdS:Sm and CdS:Sm (2%)/ZnS QDs was estimated to be ∼4 nm and ∼7 nm, respectively. Transmission electron microscopy (TEM) images revealed that the incorporation of Sm dopant did not significantly affect the size and morphology of CdS QDs, while the formation of the ZnS shell increased the particle size. XPS and XRD results confirmed the successful incorporation of Sm 3+ ions into the CdS QDs. The effect of dopant concentration on the structural and luminescent properties was studied. The emission and excitation spectra of Sm 3+ -doped CdS QDs and CdS/ZnS QDs consisted of the characteristic lines corresponding to the intra-configurational f-f transitions. The energy transfer (ET) mechanism from the host to Sm 3+ ions and the ET process through cross-relaxation between Sm 3+ ions have been elucidated. The effect of the ZnS shell on the optical stability of the Sm 3+ -doped CdS QDs was studied in detail and the results showed that the CdS:Sm (2%)/ZnS QDs retained their good emission characteristics after 376 days of fabrication. The luminescent properties of Sm-doped QDs ranging from violet to red and PL lifetime extending to milliseconds demonstrated that these QDs are the potential materials for applications in white LEDs, biomarkers, and photocatalysis., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Tunable copper doped Zn 1- x Cd x S alloy quantum dots (QDs) were successfully synthesized by the wet chemical method. A one-step method is developed to synthesize doped ternary QDs which is more preferable than a two-step method. The influence of experimental parameters like the Zn/Cd ratio and Cu dopant concentration has been investigated using various spectroscopic techniques like UV-visible, photoluminescence, X-ray diffraction and Raman spectroscopy. The absorption and emission properties can be tuned by changing the concentration of components of the ternary QDs. The high concentration of dopant completely quenched the emission of the ternary QDs. EDX gives confirmation of the elemental composition of the synthesized samples. The obtained results suggest the successful doping of the ternary QDs. Interestingly, the study results revealed that the crystal structure (ZB and/or WZ) and the dual emission of the Cu-doped Zn 1- x Cd x Se alloy QDs could be controlled by varying the dopant concentration and chemical composition of the host. Doping also leads to enhancement in emission properties and provides more stability to ternary QDs. The enhancement in the photoluminescence (PL) decay lifetime of Cu-doped ternary QDs can be advantageous for optoelectronic and biosensor applications., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

We investigated the effects of Mn doping on the crystal structure, phonon vibration, and magnetic properties of Bi 0.88 Sm 0.12 FeO 3 ceramics. Mn doping effectively modified the rhombohedral symmetry and induced a structural transition from an R 3 c rhombohedral to Pnam orthorhombic structure. Magnetic measurements revealed a weak ferromagnetic behavior, which was related to the canted antiferromagnetic order of the Pnam structure. The cycloidal spin structure of the R 3 c phase could not be suppressed by substitution of Mn at the Fe site. Studies on the self-phase transition and electric field-induced structural transition revealed many changes in coercivity and remanent magnetization, which are believed to originate from the R 3 c / Pnam phase switching along with spin frustration. Observations of the field step-dependent hysteresis loop and the ferromagnetic-like hysteresis loop after poling in an electric field provided direct evidence of phase boundary (PB) ferromagnetism and magnetic coupling at the PB., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Eu-doped CdS quantum dots (QDs) with the Eu dopant concentration in the range of 0.5-10% and zinc blende (ZB) structure were successfully synthesized by a wet chemical method. The fabricated Eu-doped CdS QDs exhibited emissions in the visible window approximately at 465, 590, 618 and 696 nm, which correspond to the excitonic emission of CdS QDs and the electronic transitions of the intra 4f 6 configuration from the 5 D 0 level to 7 F 1 , 7 F 2 and 7 F 4 levels of Eu 3+ dopant ions, respectively. Judd-Ofelt theory was used to estimate the properties of ligand field and luminescence quantum efficiency of the material. The interaction mechanism and the efficiency of the energy transfer process from CdS QDs to Eu 3+ ions were found by using Reisfeld's approximation formulas. The luminescence quenching of Eu 3+ -doped CdS QDs was studied through analysis of emission spectra and decay curves. The dominant interaction mechanism between Eu 3+ ions and energy transfer parameters have been found by fitting the decay curves to the Inokuti-Hirayama model. The cross-relaxation channels leading to the luminescence quenching of Eu 3+ have also been predicted.