Three novel lanthanide upconverting materials [LN(2,5-HPA)(2,5-PA)]_n (LN = Sm, 1; Dy, 2; Ho, 3; 2,5-H₂PA = 2,5-pyridinedicarboxylic acid) have been synthesized through hydrothermal reactions and structurally characterized by single crystal X-ray diffraction technique. These materials are crystallographically isostructural and are characteristic of three-dimensional (3-D) frameworks. The photoluminescence measurements with solid-state samples reveal that compounds 1–3 exhibit upconversion photoluminescence emissions in red, yellow and green region, respectively. The photoluminescence emission bands could be assigned to the characteristic emission of the 4f electrons intrashell transition of the ⁴G_5/2 → ⁶H_7/2, ⁴G_5/2 → ⁶H_9/2 of the Sm³⁺ ions in 1, ⁴F_9/2 → ⁶H_17/2, ⁴F_9/2 → ⁶H_15/2, ⁴F_9/2 → ⁶H_13/2 of the Dy³⁺ ions in 2, and ⁵G₆ → ⁵I₈, ⁵S₂ → ⁵I₈ of the Ho³⁺ ions in 3. An energy transfer mechanism is explained by the energy level diagrams of the lanthanide ions and the 2,5-H₂PA ligand. Solid-state UV/Vis diffuse reflectance spectra reveal that they are potential wide optical band gap semiconductors with the band gaps being of 3.73, 3.56 and 3.45 eV for 1–3, respectively. TG curves reveal that all of them are very thermal stable with the onset temperature being of 219 °C–322 °C. The photoluminescence quantum yields of compounds 1–3 were determined to be 14.1%, 18.3% and 19.6%, respectively.

三种新型镧系上转换材料[LN（2,5-HPA）（2,5-PA）] _n（LN = Sm，1 ; Dy，2 ; Ho，3 ; 2,5-H ₂ PA = 2,5-吡啶二羧酸）是通过水热反应合成的，并通过单晶X射线衍射技术对其结构进行了表征。这些材料在晶体学上是同构的，并且是三维（3-D）框架的特征。的光致发光测量与固态样品化合物，揭示1 - 3中的红色，黄色和绿色的区域表现出光致发光的上转换的排放量，分别。可以将光致发光发射带分配给4个的特征发射˚F电子intrashell所述的过渡⁴ ģ _5/2  →  ⁶ ħ _7/2，⁴ ģ _5/2  →  ⁶ ħ _9/2的SM ³⁺中的离子1，⁴ ˚F _9/2  →  ⁶ ħ _17/2，⁴ ˚F _9/2  →  ⁶ ħ _15/2，⁴ ˚F _9/2  →  ⁶ ħ _13/2所述的Dy ³⁺离子在2和⁵ ģ ₆→ ⁵我₈，⁵小号₂ → ⁵我₈何的³⁺中的离子3。通过镧系离子和2,5-H ₂ PA配体的能级图解释了能量转移的机理。固态UV /可见漫反射光谱表明，它们是潜在的宽光学带隙半导体与带隙为3.73，3.56和3.45电子伏特为1 - 3分别。TG曲线显示它们都具有很高的热稳定性，起始温度为219°C–322°C。化合物的光致发光量子产率1 - 3 分别确定为14.1％，18.3％和19.6％。