ORIGINAL ARTICLE In silico design of calixarene-based arsenic acid removal agents Gustavo Mondrago ´n-Solo ´rzano 1 • Reyes Sierra-A ´ lvarez 2 • Eddie Lo ´pez-Honorato 3 • Joaquı ´n Barroso-Flores 1 Received: 29 December 2015 / Accepted: 20 April 2016 / Published online: 27 April 2016 Ó Springer Science+Business Media Dordrecht 2016 Abstract Contamination of water resources with arsenic is a worldwide challenge with an important social impact. Development of adsorptive materials with high affinity and selectivity towards arsenic is an important and ongoing challenge. The aim of this work is to study calix[n]arenes with 4, 5, 6 and 8 rings, as well as COOH, C 2 H 4 OH, SO 3 H, t-Bu, PO 3 H 2 and PO 4 H 2 , upper-rim functional groups through computational chemistry models as tailor-made sequestering agents using pentavalent arsenate species (H 3 AsO 4 ,H 2 AsO 4 - and HAsO 4 2- ). Host–guest interaction energies (E int ) were determined using Density functional theory (DFT) calculations at the M06-2X/6-31G(d,p) level of theory carried out on host–guest adducts in order to find the most suitable candidates as extracting agents for these arsenate species. Hydrogen-bond donor groups such as SO 3 H, PO 3 H 2 and the hypothetical calixarene with R = PO 4 H 2 on the upper rim of calix[n]arenes are shown to be the most suitable functional groups for encapsulating these As(V) species under study. Keywords Calixarenes Á Arsenic Á DFT calculations Á Bioremediation Introduction A shared challenge in the arid and semi-arid areas of the United States and Mexico is the contamination of water sources with arsenic. Consumption of water contaminated with this element can have strong negative health effects, including the development of cancer [1]. The World Health Organization recommends a concentration lower than 10 lg/L for drinking water, however the natural occurrence of this element in Mexico and the United States can vary from moderate (10–50 lg/L) to high concentrations ( [ 50 lg/L) [2]. Therefore, due to the strong negative effect on humans, agriculture and industry alike, the contamina- tion of water sources with arsenic is an important challenge that needs to be addressed. There is a wide variation of techniques and materials that have been used to remove arsenic, [3] nevertheless many are complex, costly or do not work at neutral pH. Among all these options, adsorption is perhaps one of the simplest and cost-effective techniques available for the elimination of contaminants. Several adsorbents have been tested to remove arsenic, ranging from the traditional activated carbon to more complex systems such as gra- phene-nanoparticles composites. Although many of these have proven to be excellent arsenic adsorbents, for example adsorptions of 12 mg As/g sorbent can be attained using a graphene/ferrite nanoparticles composite [4], they still suffer from the same limitations as standard adsorption materials, which is lack of selectivity and saturation of their surfaces with secondary elements or molecular spe- cies that could hinder their efficiency during real condi- tions. Therefore, it would be desirable to develop adsorbent materials that could combine high surface area and active sites, as well as a strong selectivity towards specific molecules; which could reduce the effect of secondary & Joaquı ´n Barroso-Flores jbarroso@unam.mx 1 Centro Conjunto de Investigacio ´n en Quı ´mica Sustentable UAEM-UNAM, Carretera Toluca-Atlacomulco Km 14.5, Unidad San Cayetano, 50200 Toluca, Estado de Me ´xico, Mexico 2 Department of Chemical and Environmental Engineering, The University of Arizona, P.O. Box 210011, Tucson, AZ 85721, USA 3 Centro de Investigacio ´n y de Estudios Avanzados del IPN, Unidad Saltillo. Av. Industria Metalu ´rgica 1062, Parque Industrial, 25900 Ramos Arizpe, Coahuila, Mexico 123 J Incl Phenom Macrocycl Chem (2016) 85:169–174 DOI 10.1007/s10847-016-0617-0