The design, synthesis and biological evaluation of the artificial enterobactin analogue EntKL and several fluorophore-conjugates thereof are described. EntKL provides an attachment point for cargos such as fluorophores or antimicrobial...

There is no theoretical limit in using molecular networks to harvest diffusive sun photons on large areas and funnel them onto much smaller areas of highly efficient but also precious energy-converting materials. The most effective concept reported so far is based on a pool of randomly oriented, light-harvesting donor molecules that funnel all excitation quanta by ultrafast energy transfer to individual light-redirecting acceptor molecules oriented parallel to the energy converters. However, the best practical light-harvesting system could only be discovered by empirical screening of molecules that either align or not within stretched polymers and the maximum absorption wavelength of the empirical system was far away from the solar maximum. No molecular property was known explaining why certain molecules would align very effectively whereas similar molecules did not. Here, we first explore what molecular properties are responsible for a molecule to be aligned. We found a parameter derived directly from the molecular structure with a high predictive power for the alignability. In addition, we found a set of ultrafast funneling molecules that harvest three times more energy in the solar’s spectrum peak for GaInP photovoltaics. A detailed study on the ultrafast dipole moment reorientation dynamics demonstrates that refocusing of the diffusive light is based on ∼15-ps initial dipole moment depolarization followed by ∼50-ps repolarization into desired directions. This provides a detailed understanding of the molecular depolarization/repolarization processes responsible for refocusing diffusively scattered photons without violating the second law of thermodynamics.

The many-body expansion (MBE) provides an attractive fragmentation method for the efficient quantum-chemical treatment of molecular clusters. However, its convergence with the many-body order is generally slow for molecular clusters...

The design, synthesis and biological evaluation of the artificial enterobactin analogue <b>Ent_KL</b> and several fluorophore-conjugates thereof are described. <b>Ent_KL</b> provides an attachment point for cargos such as fluorophores or antimicrobial payloads. Corresponding conjugates are recognized by outer membrane siderophore receptors of Gram-negative pathogens and retain the natural hydrolyzability of the <i>tris</i>-lactone backbone, known to be key for uptake into the cytosol. Initial density-functional theory (DFT) calculations of the free energies of solvation (ΔG(sol)) and relaxed Fe-O force constants of the corresponding <b>[Fe-Ent_KL]^3- </b>complexes<b> </b>indicated a similar iron binding constant compared to natural enterobactin (<b>Ent</b>). The synthesis of <b>Ent_KL</b> was achieved via an iterative assembly based on a 3-hydroxylysine building block over 14 steps with an overall yield of 3%. A series of growth recovery assays under iron-limiting conditions with <i>Escherichia coli</i> and <i>Pseudomonas aeruginosa</i> mutant strains that are defective in natural siderophore synthesis revealed a potent concentration-dependent growth promoting effect of <b>Ent_KL</b> similar to natural <b>Ent</b>. Additionally, four cargo-conjugates differing in molecular size were able to restore growth of <i>E. coli</i> indicating an uptake into the cytosol. <i>P. aeruginosa </i>displayed a stronger uptake promiscuity as six different cargo-conjugates were found to restore growth under iron-limiting conditions. Imaging studies utilizing BODIPY_FL-conjugates, demonstrated the ability of <b>Ent_KL </b>to overcome the Gram-negative outer membrane permeability barrier and thus deliver molecular cargos via the bacterial iron transport machinery of <i>E. coli</i> and <i>P. aeruginosa</i>.

The design, synthesis and biological evaluation of the artificial enterobactin analogue <b>Ent_KL</b> and several fluorophore-conjugates thereof are described. <b>Ent_KL</b> provides an attachment point for cargos such as fluorophores or antimicrobial payloads. Corresponding conjugates are recognized by outer membrane siderophore receptors of Gram-negative pathogens and retain the natural hydrolyzability of the <i>tris</i>-lactone backbone, known to be key for uptake into the cytosol. Initial density-functional theory (DFT) calculations of the free energies of solvation (ΔG(sol)) and relaxed Fe-O force constants of the corresponding <b>[Fe-Ent_KL]^3- </b>complexes<b> </b>indicated a similar iron binding constant compared to natural enterobactin (<b>Ent</b>). The synthesis of <b>Ent_KL</b> was achieved via an iterative assembly based on a 3-hydroxylysine building block over 14 steps with an overall yield of 3%. A series of growth recovery assays under iron-limiting conditions with <i>Escherichia coli</i> and <i>Pseudomonas aeruginosa</i> mutant strains that are defective in natural siderophore synthesis revealed a potent concentration-dependent growth promoting effect of <b>Ent_KL</b> similar to natural <b>Ent</b>. Additionally, four cargo-conjugates differing in molecular size were able to restore growth of <i>E. coli</i> indicating an uptake into the cytosol. <i>P. aeruginosa </i>displayed a stronger uptake promiscuity as six different cargo-conjugates were found to restore growth under iron-limiting conditions. Imaging studies utilizing BODIPY_FL-conjugates, demonstrated the ability of <b>Ent_KL </b>to overcome the Gram-negative outer membrane permeability barrier and thus deliver molecular cargos via the bacterial iron transport machinery of <i>E. coli</i> and <i>P. aeruginosa</i>.