The separation of ethane from its corresponding ethylene is an important, challenging, and energy-intensive process in the chemical industry. Here we report a microporous metal-organic framework, iron(III) peroxide 2,5-dioxido-1,4-benzenedicarboxylate [Fe2(O2)(dobdc) (dobdc4−: 2,5-dioxido-1,4-benzenedicarboxylate)], with iron (Fe)–peroxo sites for the preferential binding of ethane over ethylene and thus highly selective separation of C2H6/C2H4. Neutron powder diffraction studies and theoretical calculations demonstrate the key role of Fe-peroxo sites for the recognition of ethane. The high performance of Fe2(O2)(dobdc) for the ethane/ethylene separation has been validated by gas sorption isotherms, ideal adsorbed solution theory calculations, and simulated and experimental breakthrough curves. Through a fixed-bed column packed with this porous material, polymer-grade ethylene (99.99% pure) can be straightforwardly produced from ethane/ethylene mixtures during the first adsorption cycle, demonstrating the potential of Fe2(O2)(dobdc) for this important industrial separation with a low energy cost under ambient conditions.

Phylogenetic relationships among the four major lineages of land plants (liverworts, mosses, hornworts, and vascular plants) remain vigorously contested; their resolution is essential to our understanding of the origin and early evolution of land plants. We analyzed three different complementary data sets: a multigene supermatrix, a genomic structural character matrix, and a chloroplast genome sequence matrix, using maximum likelihood, maximum parsimony, and compatibility methods. Analyses of all three data sets strongly supported liverworts as the sister to all other land plants, and analyses of the multigene and chloroplast genome matrices provided moderate to strong support for hornworts as the sister to vascular plants. These results highlight the important roles of liverworts and hornworts in two major events of plant evolution: the water-to-land transition and the change from a haploid gametophyte generation-dominant life cycle in bryophytes to a diploid sporophyte generation-dominant life cycle in vascular plants. This study also demonstrates the importance of using a multifaceted approach to resolve difficult nodes in the tree of life. In particular, it is shown here that densely sampled taxon trees built with multiple genes provide an indispensable test of taxon-sparse trees inferred from genome sequences.alternation of generations ͉ hornworts ͉ liverworts ͉ phylogeny ͉ taxon sampling T he origin and early evolution of land plants (embryophytes) during the mid-Ordovician to lower Silurian (480-430 million years ago) initiated the establishment of the modern terrestrial ecosystems and fundamentally altered the course of evolution of life on earth. Two important events marked this period of unprecedented innovation in plant evolution: the massive colonization of the land by plants descended from charophyte algae and the change of the dominant generation in the plant life cycle from a haploid gametophyte to a diploid sporophyte (1-5). The first event opened a vastly underexplored niche of high-intensity solar radiation and abundant CO 2 to photosynthetic life. The second event conferred on plants two abilities to adapt to a life in a water-deficient and UV-abundant terrestrial environment. One is the ability to produce a large number of genetically diverse gametes to ensure fertilization on land where sperm locomotion is hindered, and the other is the ability to mask deleterious mutations through the dominantrecessive interaction of alleles, thus allowing a large number of alleles to persist in the gene pool (2-4). Our understanding of these events hinges on our knowledge of relationships between the organisms involved in these major evolutionary transitions. Despite numerous studies using diverse approaches analyzing morphological and͞or molecular characters, relationships among early land plants remain controversial (5-19). Fossil evidence, although increasingly improved, has not helped to resolve the issues decisively (20,21).A multitude of phenomena characterizing diversification of many major clades o...

Selective separation of acetylene (CH) from carbon dioxide (CO) or ethylene (CH) needs specific porous materials whose pores can realize sieving effects while pore surfaces can differentiate their recognitions for these molecules of similar molecular sizes and physical properties. We report a microporous material [Zn(dps)(SiF)] (UTSA-300, dps = 4,4'-dipyridylsulfide) with two-dimensional channels of about 3.3 Å, well-matched for the molecular sizes of CH. After activation, the network was transformed to its closed-pore phase, UTSA-300a, with dispersed 0D cavities, accompanied by conformation change of the pyridyl ligand and rotation of SiF pillars. Strong C-H···F and π-π stacking interactions are found in closed-pore UTSA-300a, resulting in shrinkage of the structure. Interestingly, UTSA-300a takes up quite a large amounts of acetylene (76.4 cm g), while showing complete CH and CO exclusion from CH under ambient conditions. Neutron powder diffraction and molecular modeling studies clearly reveal that a CH molecule primarily binds to two hexafluorosilicate F atoms in a head-on orientation, breaking the original intranetwork hydrogen bond and subsequently expanding to open-pore structure. Crystal structures, gas sorption isotherms, molecular modeling, experimental breakthrough experiment, and selectivity calculation comprehensively demonstrated this unique metal-organic framework material for highly selective CH/CO and CH/CH separation.