The growing interest in synthetic peptides has prompted the development of viable methods for their sustainable production. Currently, large amounts of toxic solvents are required for peptide assembly from protected building blocks, and switching to water as a reaction medium remains a major hurdle in peptide chemistry. We report an aqueous solid‐phase peptide synthesis strategy that is based on a water‐compatible 2,7‐disulfo‐9‐fluorenylmethoxycarbonyl (Smoc) protecting group. This approach enables peptide assembly under aqueous conditions, real‐time monitoring of building block coupling, and efficient postsynthetic purification. The procedure for the synthesis of all natural and several non‐natural Smoc‐protected amino acids is described, as well as the assembly of 22 peptide sequences and the fundamental issues of SPPS, including the protecting group strategy, coupling and cleavage efficiency, stability under aqueous conditions, and crucial side reactions.

Crystalline complexes of NH4+PF6– with trimethyl‐ and triethylbenzene‐based tripodal compounds, bearing either pyrazole or indazole groups, were prepared and characterized by X‐ray diffraction studies. The supramolecular motifs observed in the crystal structures and the conformations of the tripodal molecules have been the subject of a detailed analysis and are described in this paper. The pyrazole‐bearing side arms of the hosts with a trimethylbenzene scaffold are arranged in an aaa fashion and form a cavity including the ammonium ion. In the case of the triethylbenzene derivatives, the fully alternating arrangement of the pyrazole/indazole and ethyl groups is observed and by taking the ethyl groups into account, the conformation can be defined as ab′ab′ab′. The conformations observed in the crystals of the free host molecules can be defined as ab′ab′ba′ with the indazole‐bearing arms arranged in an aab fashion. The crystal packings of the complexes are, among other things, characterized by the presence of NH···F and CH···F hydrogen bonds as well as by CBr···N and CBr···π halogen bonds in the case of the bromo‐substituted derivatives.

X-ray analyses of a series of benzene-based tripodal molecules1–9provide interesting insights into the molecular recognition phenomena and give information about the different conformations which adopt the molecules in the solvent-free crystals and in solvates.

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