Metal Organic Frameworks (M0Fs) are hybrid materials, usually crystalline, consisting of metallic species or clusters, connected by polytopic organic ligands originating bi or tridimensional porous structures. In this work, Gd-1,4-BDC-MOFs doped with 5% mol Eu3+ were synthesized via solvothermal method at 180 degrees C. The effect of the synthesis time (3, 5 or 7 days) on the microstructure and photophysical properties of the obtained MOFs were evaluated. It was found that porous agglomerates were formed within three days, gradually changing their morphology to rod-like crystals within seven days. The photoluminescence excitation and emission spectra revealed an efficient energy transfer from the ligand to the Eu3+ levels (antenna effect), what is not expected for 1,4-BDC2- in a Eu(III)-based MOFs. We concluded that the presence of highly paramagnetic Gd3+ ions in the matrix enhanced the antenna effect, resulting in a strong red emission. (C)2017 Elsevier B.V. All rights reserved.