Solid-state studies evaluating intermolecular geometries in methylated nucleobases are not extensively explored. In the course of the present study, we have solved the crystal structures of 1-, 3- and 7-methylated adenines and guanines, including the monohydrate and sesquihydrate forms of 3-methyladenine and 3-methylguanine, respectively, by means of single-crystal X-ray diffraction and synchrotron/laboratory X-ray powder diffraction (XRPD). In situ high temperature XRPD experiments, coupled with differential thermal analysis/thermogravimetry (DTA/TG) measurements, allowed for monitoring crystallographic changes after water removal of N3-methylated compounds, and the discovery of a high temperature polymorph in the case of 3-methyladenine. Our findings indicate that H-bonding schemes describe ribbon planar motifs of molecules in the majority of cases, or linear double-bonded strands of molecules in a few cases. π-π stacking interactions were compared with existing findings of theoretical calculations and existing crystallographic data, showing how N-methylated purine bases follow the trend predicted by Hunter and Sanders, 1990. The present study provides the first systematic experimental insights into the solid state of the presented compounds.

While tracing the geological provenance of Maya jadeitite-jade is key to understanding Mesoamerican exchange and extraction, distinguishing between the north (NMM) and south (SMM) Motagua sources presents significant challenges. This difficulty is due to shared mineralogical traits and the limitations of applying bulk whole rock trace element determination to invaluable archaeological objects. This study proposes an integrated statistical framework combining existing whole rock reference data with new Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) trace element measurements. We characterized 39 geological reference samples from both NMM and SMM, as well as 16 archaeological fragments from seven Maya sites. Despite complex multi-generation growth and local geochemical heterogeneities revealed by cathodoluminescence and LA-ICP-MS, a Partial Least Squares Discriminant Analysis (PLS-DA) model successfully discriminated between NMM and SMM sources with 89% accuracy using thirteen key trace elements (Th, Zn, La, Hf, Ce, Tm, Yb, Ni, Sr, Lu, Eu, Pr, Er). Application of this model to archaeological samples suggests a predominant exploitation of NMM sources across the Maya Highlands, Lowlands, and Pacific coast, with the exception of the El Tuno workshop, which shows more affinity with SMM. This approach validates LA-ICP-MS as a robust tool for jade provenance studies, overcoming the biases of accessory minerals inherent in whole rock analyses and offering a transferable strategy for archaeometric research.