Collective adaptability in a replication network of minimal nucleobase sequences.

A major challenge for understanding the origins of life is to explore how replication networks can engage in an evolutionary process. Herein, we shed light on this problem by implementing a network constituted by two different types of extremely simple biological components: the amino acid cysteine and the canonical nucleobases adenine and thymine, connected through amide bonds to the cysteine amino group and oxidation of its thiol into three possible disulfides. Supramolecular and kinetic analyses revealed that both self- and mutual interactions between such dinucleobase compounds drive their assembly and replication pathways. Those pathways involving sequence complementarity led to enhanced replication rates, suggesting a potential bias for selection. The interplay of synergistic dynamics and competition between replicators was then simulated, under conditions that are not easily accessible with experiments, in an open reactor parametrized and constrained with the unprecedentedly complete experimental kinetic data obtained for our replicative network. Interestingly, the simulations show bistability, as a selective amplification of different species depending on the initial mixture composition. Overall, this network configuration can favor a collective adaptability to changes in the availability of feedstock molecules, with disulfide exchange reactions serving as 'wires' that connect the different individual auto- and cross-catalytic pathways.

Monitoring organic reactions by UF-NMR spectroscopy.

Standard 2D NMR experiments suffer from the many t1 increments needed for spectra with sufficient digital resolution in the indirect dimension. Despite the different methodological approaches to overcome this problem, these increments have prevented studies of fast reactions. The development of ultrafast NMR (UF-NMR) has decisively speeded up the time scale of standard NMR to allow the study of organic reactions as they happen in real time to reveal mechanistic details. This mini-review summarizes the results achieved in monitoring organic reactions through this exciting technique.

N-(4-Chloro-phen-yl)maleimide.

In the title compound, C(10)H(6)ClNO(2), the dihedral angle between the benzene and maleimide rings is 47.54 (9)°. Mol-ecules form centrosymmetric dimers through C-H⋯O hydrogen bonds, resulting in rings of graph-set motif R(2) (2)(8) and chains in the [100] direction. Mol-ecules are also linked by C-H⋯Cl hydrogen bonds along [001]. In this same direction, mol-ecules are connected to other neighbouring mol-ecules by C-H⋯O hydrogen bonds, forming edge-fused R(4) (4)(24) rings.

N-(3-Chloro-phen-yl)maleimide.

The title compound, C(10)H(6)ClNO(2), has a dihedral angle of 46.46 (5)° between the benzene and maleimide rings. A short inter-molecular halogen-oxygen contact is observed, with a Cl⋯O distance of 3.0966 (13) Å. Both CO groups are involved in two C-H⋯O inter-actions, which gives rise to sheets parallel to (100). In addition, these sheets exhibit a π-π stacking inter-action between the benzene and maleimide rings [mean inter-planar distance of 3.337 (3) Å].