VUV spectroscopic properties of rare-earth (RE3+ = Sm3+, Eu3+, Tb3+, Dy3+) -activated layered borate Ba6Gd9B79O138

Vacuum ultraviolet (VUV) spectroscopic properties of rare-earth RE³⁺- activated (RE³⁺ = Sm³⁺, Eu³⁺, Tb³⁺ and Dy³⁺) Ba₆Gd₉B₇₉O₁₃₈ borates (BGBO) are investigated. The strong absorption bands in the VUV range of un-doped and RE³⁺-activated BGBO were observed. The band range from 140 to 200 nm with a peak at about 173 nm results from the host lattice absorption. For Sm³⁺-activated BGBO, the charge transfer transition from O^2- to Sm³⁺ was observed at 202 nm. In addition, it exhibits bright red emission originating from the Sm³⁺ f-f transitions of ⁴G_5/2 → ⁶H_J (J = 5/2, 7/2 and 9/2). The O^2--Eu³⁺ charge transfer (CT) at 249 nm is observed in the excitation spectrum for Eu³⁺-doped BGBO. For Tb³⁺-activated BGBO, the broad bands around 208 and 230 nm are due to the spin-allowed and spin-forbidden f-d transitions of Tb³⁺, respectively. In addition, the absence of the f-d transitions of Sm³⁺ and Dy³⁺ in the excitation spectra probably due to the photo-ionization effect. It is demonstrated that there are energy transfers from the BGBO host lattice to the luminescent activators depending on the activators.     

Synthesis and characterization of monodisperse spherical SiO2@RE2O3 (RE=rare earth elements) and SiO2@Gd2O3:Ln (Ln=Eu, Tb, Dy, Sm, Er, Ho) particles with core-shell structure

Spherical SiO₂ particles have been coated with rare earth oxide layers by a Pechini sol-gel process, leading to the formation of core-shell structured SiO₂@RE₂O₃ (RE=rare earth elements) and SiO₂@Gd₂O₃:Ln³⁺ (Ln=Eu, Tb, Dy, Sm, Er, Ho) particles. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), photoluminescence (PL), and cathodoluminescence spectra as well as lifetimes were used to characterize the resulting SiO₂@RE₂O₃ (RE=rare earth elements) and SiO₂@Gd₂O₃:Ln³⁺ (Eu³⁺, Tb³⁺, Dy³⁺, Sm³⁺, Er³⁺, Ho³⁺) samples. The obtained core-shell phosphors have perfect spherical shape with narrow size distribution (average size ca. 380 nm), smooth surface and non-agglomeration. The thickness of shells could be easily controlled by changing the number of deposition cycles (40 nm for two deposition cycles). Under the excitation of ultraviolet, the Ln³⁺ ion mainly shows its characteristic emissions in the core-shell particles from Gd₂O₃:Ln³⁺ (Eu³⁺, Tb³⁺, Sm³⁺, Dy³⁺, Er³⁺, Ho³⁺) shells.     

Investigation on the upconversion luminescence of Sr3AlO4F:Yb3+, Er3+, Ho3+ phosphors

To develop new emission-tunable upconversion (UC) phosphors, the Sr₃AlO₄F:5%Yb³⁺, xEr³⁺, yHo³⁺ (0 ≤ x ≤ 1%, 0 ≤ y ≤ 1%) samples were prepared by conversional solid-state reaction method, and their luminescence properties upon 980 nm excitation were studied. Upon 980 nm excitation, Yb³⁺-Er³⁺ codoped Sr₃AlO₄F shows a predominant emission peak between 645 and 700 nm which is attributed to the ⁴F_9/2-⁴I_15/2 transition of Er³⁺, and the Er³⁺ green emissions have been almost quenched. In this case, the yellowish green emitting light is obtained. The possible reason was interpreted by the energy level diagram and the proposed UC mechanism. For Yb³⁺-Ho³⁺ codoped Sr₃AlO₄F, three emissions are observed obviously which are all derived from the Ho³⁺ ion. The corresponding chromaticity coordinates indicate a red emission has been gained. To realize the tunable emission, the typical Sr₃AlO₄F:5%Yb³⁺, 0.2%Er³⁺, 1%Ho³⁺ phosphor was developed, and its emission spectrum includes the emission peaks of both Er³⁺ and Ho³⁺. Correspondingly, the sample gives a yellow emission.     

Infrared absorption spectra of Er3+-doped Al2O3 nanopowders by the sol-gel method

The Er³⁺-doped Al₂O₃ nanopowders have been prepared by the sol-gel method, using the aluminium isopropoxide [Al(OC₃H₇)₃]-derived γ-AlOOH sols with addition of the erbium nitrate [Er(NO₃)₃·5H₂O]. The five phases of γ-(Al,Er)₂O₃, θ-(Al,Er)₂O₃, α-(Al,Er)₂O₃, ErAlO₃, and Al₁₀Er₆O₂₄ were detected with the 0–20 mol% Er³⁺-doped Al₂O₃ nanopowders at the different sintering temperature of 600–1200°C. The average grain size was increased from about 5 to 62 nm for phase transformation of undoped γ-Al₂O₃→α-Al₂O₃ at the sintering temperature from 600 to 1200°C. At the same sintering temperature, average grain size was decreased with increase of the Er³⁺ doping concentration. Infrared absorption spectra of γ-Al₂O₃ and θ-Al₂O₃ nanopowders showed the two broad bands of 830–870 and 550–600 cm⁻¹, the three broad bands of 830–870, 750–760, and 550–600 cm⁻¹, respectively. The infrared absorption spectra for the α-Al₂O₃ nanopowder showed three characteristic bands, 640, 602, and 453 cm⁻¹. The two characteristic bands of 669 and 418 cm⁻¹ for Er₂O₃ clusters were observed for the Er³⁺-doped Al₂O₃ nanopowders when Er³⁺ doping concentration was increased up to 2 mol%. The 796, 788, 725, 692, 688, 669, 586, 509, 459, and 418 cm⁻¹ are the characteristic bands of Al₁₀Er₆O₂₄ phase.     

Preparation and spectroscopic properties of nanostructured glass-ceramics containing Yb3+, Er3+ ions and Co2+-doped spinel nanocrystals

Transparent glass-ceramics with Yb³⁺, Er³⁺ ions in glass matrix and tetrahedral Co²⁺-doped MgAl₂O₄ nanocrystals were synthesized. XRD patterns and FESEM micrograph of the glass-ceramics showed that MgAl₂O₄ nanocrystals (sizes of 10–20 nm) are uniformly dispersed in SiO₂ glass matrix. Absorption and emission spectra of the glass-ceramics indicated that Yb³⁺, Er³⁺ remain in SiO₂ glass matrix, while Co²⁺ occupied tetrahedral sites in MgAl₂O₄ nanocrystals, and can function as saturable absorber for Er³⁺. Transparent Co²⁺, Yb³⁺, Er³⁺ co-doped glass-ceramics possesses the spectral requirements and should be a potential laser material used for self-Q-switched microchip laser operating at 1.5–1.6 μm.     

Investigation of Er3+, Yb3+, Nd3+ doped yttrium calcium oxyborate for photon upconversion applications

In this work, investigation have been done on polycrystalline yttrium calcium oxyborate (YCa₄O(BO₃)₃) for the realization of existence of second harmonic generation and other photon upconversion processes as concurrent effect with the aid of Er, Yb, Nd trivalent lanthanide ions. Pure, Er:Yb co-doped and Er:Yb:Nd triply-doped YCa₄O(BO₃)₃ samples were prepared through solid state reaction and the phase identification has been done using powder X-ray diffraction spectral analysis. FTIR spectra show that the dopants increases the absorption of functional groups and modifies the lattice vibrational modes of YCa₄O(BO₃)₃. The spectral overlap of optical absorption bands of Er³⁺, Yb³⁺, Nd³⁺ ions in 840 nm–1070 nm region indicates the prospect of energy transfer between these ions. The photoluminescence spectrum of Er:Yb:Nd triply doped sample show good enhancement compared to pure and Er:Yb co-doped YCa₄O(BO₃)₃ samples. In the photon upconversion test carried out using 1064 nm Nd:YAG laser YCa₄O(BO₃)₃:Er:Yb:Nd sample produced green light with efficiency higher than the other two samples. Surface morphology of the samples was recorded using field emission scanning electron microscope and analysed. The elemental composition of the samples has been confirmed by energy dispersive X-ray spectral analysis.     

Mangifera indica leaf-assisted biosynthesis of well-dispersed silver nanoparticles

Natural fluorite crystals containing oxygen impurities are colored electrolytically by using a pointed cathode and a flat anode at various temperatures and voltages. F and F₂ color centers are produced in colored fluorite crystals. O²⁻–V_a⁺, O²⁻–V_a⁺ aggregate, Yb²⁺, Ce³⁺ and Sm²⁺ absorption bands are observed in absorption spectra of uncolored fluorite crystals. O²⁻–V_a⁺, O²⁻–V_a⁺ aggregate, Yb²⁺, Ce³⁺, Sm²⁺, F, M (F₂) absorption bands and group of four absorption bands are observed simultaneously in absorption spectra of colored fluorite crystals. Current−time curve for electrolytic coloration of natural fluorite crystal and its relationship with electrolytic coloration process are given. Production and conversion of color centers are explained.     

Synthesis and Infrared Multi‐band Absorption Properties of Core‐shell NaYF4:Yb3+, Er3+@SiO2 Nanoparticles

Due to the unique size effects, nanomaterials in infrared absorption have attracted much attention for their strong absorption in the infrared region. To achieve the infrared multi‐band absorption, we propose to synthesize a core‐shell structure nanomaterial consisting of NaYF₄:Yb³⁺, Er³⁺ core and a layer of SiO₂ as shell. A series of NaYF₄:Yb³⁺, Er³⁺ nanocrystals were synthesized through hydrothermal method by adjusting the ratio of citric acid(CA)‐to‐NaOH, and the effects of CA concentration, and NaOH concentration were studied in detail. NaYF₄:Yb³⁺, Er³⁺@SiO₂ nanoparticles were synthesized by sol‐gel method using TEOS as silica source. The results show that the core‐shell NaYF₄:Yb³⁺, Er³⁺@SiO₂ nanoparticles were successfully synthesized. Up‐conversion spectra of these nanoparticles were recorded with 980 nm laser excitation under room temperature. There are no changes of the emission centers of nanoparticles before or after silica coating, but the emission intensities of nanoparticles after silica coating are weakened. Furthermore, the property of infrared multi‐band absorption was tested through ultraviolet‐visible‐near infrared spectrophotometer and infrared absorption spectra. The results illustrate that the multi‐band infrared absorption nanomaterial was successfully synthesized.     

Luminescent-technique study on the structure of cation subsystem in the ionic conductor Na5RESi4O12 (RE is a rare-earth cation Tb3+, Ho3+, Er3+, Gd3+, Eu3+)

Results of experimental studies of luminescence in a group of materials with common formula Na₅RESi₄O₁₂ (RE is a rare-earth cation Tb³⁺, Ho³⁺, Er³⁺, Gd³⁺, Eu³⁺ entering the stoichiometric formula of the substance) are summarized. The luminescence spectra give information on the mobile-cation sublattice structure and dynamics. It follows from experimental results that the current opinion on the disordering of mobile sublattice is not quite correct. At relatively low temperatures (T < 100 K), a small number of typical local configurations of cations can be elucidated, which in aggregate can describe the Na⁺ cation sublattice to rather high degree of accuracy. At higher temperatures, the number of spectral lines and their positions change, which formally corresponds to changes in the symmetry of sites of the lattice, hence, is the sign of a second order phase transition. This phenomenon is given an explanation based on a suggestion on the local dynamic averaging of the mobile cation electrical fields.     

VUV-UV Photoluminescence Spectra of Strontium Orthophosphate Doped with Rare Earth Ions

The measurements of VUV-UV photoluminescence emission (PL) and photoluminescence excitation (PLE) spectra of rare earth ions activated strontium orthophosphate [Sr₃(PO₄)₂:RE, RE = Ce, Sm, Eu, Tb] are performed. Whenever the samples are excited by VUV or UV light, the typical emission of Ce³⁺, Sm³⁺, Eu³⁺, Eu²⁺ and Tb³⁺ ions can be observed in PL spectra, respectively. The charge transfer bands (CTBs) of Sm³⁺ and Eu³⁺ are found, respectively, peaking at 206 and 230 nm. The absorption bands peaking in the region of 150-160 nm are assigned to the host lattice sensitization bands, i.e., the band-to-band transitions of PO₄³⁻ grouping in Sr₃(PO₄)₂. It is speculated that the first f-d transitions of Sm³⁺ (Eu³⁺), and the CTB of Tb³⁺are, respectively, located around 165 (1 4 3) and 167 nm by means of VUV-UV PLE spectra and relational empirical formula, these f-d transitions or CT bands are included in the bands with the maxima at 150-160 nm, respectively. The valence change of europium from trivalent to divalent in strontium orthophosphate prepared in air is observed by VUV-UV PL and PLE spectra.     

Judd-Ofelt analysis and multiphonon relaxations of rare earth ions in fluorohafnate glasses

The optical properties of fluorohafnate glasses doped with Pr³⁺, Nd³⁺, Sm³⁺, Dy³⁺, Ho³⁺, Er³⁺, and Tm³⁺ have been studied. From optical absorption measurements and using Judd-Ofelt theory, JO parameters Ω₂, Ω₄, and Ω₆ have been obtained. The Ω₂ values indicate that fluorohafnate glasses present a less ionic character than fluorozirconates. Multiphonon emission probabilities for several levels of Er³⁺ and Ho³⁺ ions were determined by the difference between the measured rates and the calculated radiative transition probabilities. The results are almost the same as those found in fluorozirconates. Multiphonon emission probabilities are in agreement with the energy-gap law followed by rare-earth ions in crystals and glasses.     

Synthesis of lanthanide carbonates

The normal carbonates of La³⁺, Nd³⁺, Sm³⁺, Eu³⁺, Gd³⁺, Dy³⁺ and Ho³⁺ have been synthesized by the reaction of an aqueous suspension of the lanthanide oxide, M₂O₃, with CO₂ under supercritical conditions. The effect of temperature, between 25 and 50 °C, and pressure, from 68 to 240 atm, on the extent of conversion of the oxide to the carbonate has been investigated. Yields of 95% or better of the normal carbonates were obtained at a pressure of 100 atm after the reaction was carried out for 1 h. The higher the concentration of CO₂ dissolved in the aqueous phase, the higher the yield. The oxides of Pr³⁺, Tb³⁺, Er³⁺ and Yb³⁺, as well as ZrO₂ and CeO₂, either did not react at all or gave very low yields of carbonates under the experimental conditions that were employed.     

Easy and General Synthesis of Large‐Sized Mesoporous Rare‐Earth Oxide Thin Films by ′Micelle Assembly′

Large‐sized (ca. 40 nm) mesoporous Er₂O₃ thin films are synthesized by using a triblock copolymer poly(styrene‐b‐2‐vinyl pyridine‐b‐ethylene oxide) (PS‐b‐P2VP‐b‐PEO) as a pore directing agent. Each block makes different contributions and the molar ratio of PVP/Er³⁺ is crucial to guide the resultant mesoporous structure. An easy and general method is proposed and used to prepare a series of mesoporous rare‐earth oxide (Sm₂O₃, Dy₂O₃, Tb₂O₃, Ho₂O₃, Yb₂O₃, and Lu₂O₃) thin films with potential uses in electronics and optical devices.     

Synthesis of New LnxBi2–xSe3 (Ln: Sm3+, Eu3+, Gd3+, Tb3+) Nanomaterials and Investigation of Their Optical Properties

New Ln_xBi_2–xSe₃ (Ln: Sm³⁺, Eu³⁺, Gd³⁺, Tb³⁺) based nanomaterials were synthesized by a co‐reduction method. Powder XRD patterns indicate that the Ln_xBi_2–xSe₃ crystals (Ln = Sm³⁺, Eu³⁺, x = 0.00–0.44 and Ln = Gd³⁺, Tb³⁺, x = 0.00–0.50) are isostructural with Bi₂Se₃. The cell parameter c decreases for Ln = Eu³⁺, Gd³⁺, Tb³⁺ upon increasing the dopant content (x), while a slightly increases. Changes in lattice parameters could be related to the radii of cations. SEM images show that doping of the lanthanide ions in the lattice of Bi₂Se₃ generally results in nanoflowers. For the terbium compound two kinds of morphologies (nanoflowers and nanobelts) were observed. UV/Vis absorption and emission spectroscopy reveals mainly electronic transitions of the Ln³⁺ ions. Emission spectra show intense transitions from the excited to the ground state of Ln³⁺ and energy transfer from the Bi₂Se₃ lattice. Emission spectra of europium‐doped materials, in addition to the characteristic red emission peaks of Eu³⁺, show an intense blue emission band centered at 432 nm, originating from the 4f⁶5d¹ to 4f⁷ configuration in Eu²⁺. EPR measurements confirm the existence of Eu²⁺ in the materials. Interestingly, for all samples starting at low Ln³⁺ concentration, the emission intensity rises to a maximum at a Ln³⁺ concentration of x = 0.2 and falls again steadily to a minimum at x = 0.45.     

Intense Upconversion Luminescence of CaSc2O4:Ho3+/Yb3+ from Large Absorption Cross Section and Energy‐Transfer Rate of Yb3+

Concentration‐optimized CaSc₂O₄:0.2 % Ho³⁺/10 % Yb³⁺ shows stronger upconversion luminescence (UCL) than a typical concentration‐optimized upconverting phosphor Y₂O₃:0.2 % Ho³⁺/10 % Yb³⁺ upon excitation with a 980 nm laser diode pump. The ⁵F₄+⁵S₂→⁵I₈ green UCL around 545 nm and ⁵F₅→⁵I₈ red UCL around 660 nm of Ho³⁺ are enhanced by factors of 2.6 and 1.6, respectively. On analyzing the emission spectra and decay curves of Yb³⁺: ²F_5/2→²F_7/2 and Ho³⁺: ⁵I₆→⁵I₈, respectively, in the two hosts, we reveal that Yb³⁺ in CaSc₂O₄ exhibits a larger absorption cross section at 980 nm and subsequent larger Yb³⁺: ²F_5/2→Ho³⁺: ⁵I₆ energy‐transfer coefficient (8.55×10^?17 cm³ s^?1) compared to that (4.63×10^?17 cm³ s^?1) in Y₂O₃, indicating that CaSc₂O₄:Ho³⁺/Yb³⁺ is an excellent oxide upconverting material for achieving intense UCL.     

Upconversion Luminescence Properties of a LiNb0.3Ta0.7O3:Er3+,Yb3+ Ceramic

A co-doped LiNb_0.3Ta_0.7O₃:Er³⁺,Yb³⁺ ceramic was prepared by a high temperature solid state procedure. Under the excitation of 980 nm laser radiation, intense 660 nm red light and 550 nm green light emissions corresponding to the ⁴F_9/2→⁴I_15/2 and ²H_11/2/⁴S_3/2→⁴I_15/2 transitions of Er³⁺ were observed. The change of Yb³⁺ concentration has a more significant influence on luminous intensity than the Er³⁺ concentration. The emission of red and green lights is attributed to a two-photon process. The upconversion luminescence mechanisms were analyzed in detail.     

Absorption and fluorescence of Ho3+ IN La2S3·3Ga2S3

Absorption bands of Ho³⁺ in vitreous La₂S₃·3Ga₂S₃ in the range 500 to 2000 nm were assigned. Excitation spectra reveal additional levels ⁵G₆ and ⁵F₃ obscured by the intrinsic absorption of the glass. The Ho³⁺ emission in chalcogenide glasses is more intense than in oxide glasses due to smaller non radiative relaxation as predicted by the theory of multiphonon relaxation.     

Interaction of rare-earth oxides with binary molten mixtures of zirconium and alkali metal fluorides

Isothermal saturation, inductively coupled plasma mass spectrometry (ICP-MS), and X-ray powder diffraction were used to study solubilities of La₂O₃, Sm₂O₃, and Ho₂O₃ in the eutectic mixtures of LiF-ZrF₄, NaF-ZrF₄, and KF-ZrF₄ systems at temperatures from 873 to 1073 K. The solubilities of rare earth oxides in the molten fluorozirconate systems studied decrease in the increasing order of Ln³⁺ ion radii and in the increasing order of alkali metal cation radii in the binary mixture. The thermodynamic parameters of dissolution calculated for the oxides imply the dominance of a chemical dissolution mechanism, and this implication was supported by X-ray powder diffraction data.     

Two color up-conversion emissions of Er<Superscript>3+</Superscript>-doped Al<Subscript>2</Subscript>O<Subscript>3</Subscript> nanopowders prepared by non-aqueous sol-gel method

Er³⁺-doped Al₂O₃ nanopowders have been prepared by the non-aqueous sol-gel method using the aluminum isopropoxide as precursor, acetylacetone as a chelating agent, nitric acid as a catalyzer, and hydrated erbium nitrate as a dopant under isopropanol environment. The different phase structure, including three crystalline types of (Al, Er)₂O₃ phases, α, γ, θ, and an Er–Al–O stoichiometric compound phase, Al₁₀Er₆O₂₄, was observed for the 0.01–0.5 mol% Er³⁺-doped Al₂O₃ nanopowders at the sintering temperature of 1,000 °C. The green and red up-conversion emissions centered at about 523, 545 and 660 nm, corresponding respectively to the ²H_11/2, ⁴S_3/2→⁴I_15/2 and ⁴F_9/2→⁴I_15/2 transitions of Er³⁺, were detected by a 978 nm semiconductor laser diodes excitation. With increasing Er³⁺ doping concentration from 0.01 to 0.1 mol%, the intensity of the green and red emissions increased with a decrease of the intensity ratio of the green to red emission. When the Er³⁺ doping concentration rose to 5 mol%, the intensity of the green and red emissions decreased with an increase of their intensity ratio. The maximum intensity of both the green and red emissions with the minimum of intensity ratio was obtained, respectively, for the 0.1 mol% Er³⁺-doped Al₂O₃ nanopowders composed of a single α-(Al,Er)₂O₃ phase. The intensity ratio of the green emission at 523 and 545 nm increased monotonously for all Er³⁺ doping concentrations. The two-photon absorption up-conversion process was involved in the green and red up-conversion emissions of the Er³⁺-doped Al₂O₃ nanopowders.     

DNA Intercalating Near-Infrared Luminescent Lanthanide Complexes Containing Dipyrido[3,2-a:2′,3′-c]phenazine (dppz) Ligands: Synthesis,Crystal Structures,Stability, Luminescence Properties and CT-DNA Interaction

In order to create near-infrared (NIR) luminescent lanthanide complexes suitable for DNA-interaction, novel lanthanide dppz complexes with general formula [Ln(NO₃)₃(dppz)₂] (Ln = Nd³⁺, Er³⁺ and Yb³⁺; dppz = dipyrido[3,2-a:2′,3′-c]phenazine) were synthesized, characterized and their luminescence properties were investigated. In addition, analogous compounds with other lanthanide ions (Ln = Ce³⁺, Pr³⁺, Sm³⁺, Eu³⁺, Tb³⁺, Dy³⁺, Ho³⁺, Tm³⁺, Lu³⁺) were prepared. All complexes were characterized by IR spectroscopy and elemental analysis. Single-crystal X-ray diffraction analysis of the complexes (Ln = La³⁺, Ce³⁺, Pr³⁺, Nd³⁺, Eu³⁺, Er³⁺, Yb³⁺, Lu³⁺) showed that the lanthanide’s first coordination sphere can be described as a bicapped dodecahedron, made up of two bidentate dppz ligands and three bidentate-coordinating nitrate anions. Efficient energy transfer was observed from the dppz ligand to the lanthanide ion (Nd³⁺, Er³⁺ and Yb³⁺), while relatively high luminescence lifetimes were detected for these complexes. In their excitation spectra, the maximum of the strong broad band is located at around 385 nm and this wavelength was further used for excitation of the chosen complexes. In their emission spectra, the following characteristic NIR emission peaks were observed: for a) Nd³⁺: ⁴F_3/2 → ⁴I_9/2 (870.8 nm), ⁴F_3/2 → ⁴I_11/2 (1052.7 nm) and ⁴F_3/2 → ⁴I_13/2 (1334.5 nm); b) Er³⁺: ⁴I_13/2 → ⁴I_15/2 (1529.0 nm) c) Yb³⁺: ²F_5/2 → ²F_7/2 (977.6 nm). While its low triplet energy level is ideally suited for efficient sensitization of Nd³⁺ and Er³⁺, the dppz ligand is considered not favorable as a sensitizer for most of the visible emitting lanthanide ions, due to its low-lying triplet level, which is too low for the accepting levels of most visible emitting lanthanides. Furthermore, the DNA intercalation ability of the [Nd(NO₃)₃(dppz)₂] complex with calf thymus DNA (CT-DNA) was confirmed using fluorescence spectroscopy.