A material grafted on its surface with an ultra-thin layer, which is a monomolecular layer, of one or more substituted (thia)calix[n]aryls, as represented below wherein the thickness of the ultra-thin layer does not exceed twice the height of the grafted (thia)calix[n]aryls, the height being the distance between the surface that is grafted and the part of the grafted (thia)calix[n]aryl molecule that is furthest away from the surface before any introduction of substituents during an optional post-functionalization step, n is the number of aryl moieties forming the (thia)calix[n]aryl ring being 4, 5, or 6; X represents CH 2 , S, SO or SO 2 ; R 1 , R 2 , R 3 , R 4 , R 5 and R 6 each independently represent hydrogen or C 1-30 alkyl optionally substituted with one or more substituents each independently selected from the group consisting of halo, carboxylic acid ester, alkyl or benzyl thioester, alkenyl, alkynyl, C 1-30 alkoxy, aryl, substituted aryl wherein the substituent is fluoro or cyano or C 1-30 alkyl or C 1-30 alkoxy, -N 3 , cyano, carboxylic acid, carboxylic acid amide, -OH, amino, amido, imino, carbamate, ureido, thioureido, substituted disulfide, heterocyclic, amino acid and amino acid derivative, peptide, phosphine or phosphine oxide, crown ether, aza-crown ether, cryptand, porphyrin, calixarene, cyclodextrin, resorcinarene, saccharide, and polyethylene glycol; and wherein two or more of R 1 , R 2 , R 3 , R 4 , R 5 and R 6 may be covalently linked either directly or by a bridge that includes oxygen, phosphine, phosphine oxide, sulfur, SO, SO 2 , amino, imino, amido, ureido, thioureido, ester, thioester, alkene, alkyne or alkyl; Y 1 -, Y 2 -, Y 3 -, Y 4 - and Y 5 - each independently represent a covalent link with the material's surface, or Y 1 -, Y 2 -, Y 3 -, Y 4 - and Y 5 - are each independently selected from the group consisting of OH, hydrogen, NO 2 , halogen, N 2 + A - , C 1-30 alkyl, carboxylic acid and derivatives thereof, acyl, -N 3 alkenyl or alkynyl. the thickness of the ultra-thin layer does not exceed twice the height of the grafted (thia)calix[n]aryls, the height being the distance between the surface that is grafted and the part of the grafted (thia)calix[n]aryl molecule that is furthest away from the surface before any introduction of substituents during an optional post-functionalization step, n is the number of aryl moieties forming the (thia)calix[n]aryl ring being 4, 5, or 6; X represents CH 2 , S, SO or SO 2 ; R 1 , R 2 , R 3 , R 4 , R 5 and R 6 each independently represent hydrogen or C 1-30 alkyl optionally substituted with one or more substituents each independently selected from the group consisting of halo, carboxylic acid ester, alkyl or benzyl thioester, alkenyl, alkynyl, C 1-30 alkoxy, aryl, substituted aryl wherein the substituent is fluoro or cyano or C 1-30 alkyl or C 1-30 alkoxy, -N 3 , cyano, carboxylic acid, carboxylic acid amide, -OH, amino, amido, imino, carbamate, ureido, thioureido, substituted disulfide, heterocyclic, amino acid and amino acid derivative, peptide, phosphine or phosphine oxide, crown ether, aza-crown ether, cryptand, porphyrin, calixarene, cyclodextrin, resorcinarene, saccharide, and polyethylene glycol; and wherein two or more of R 1 , R 2 , R 3 , R 4 , R 5 and R 6 may be covalently linked either directly or by a bridge that includes oxygen, phosphine, phosphine oxide, sulfur, SO, SO 2 , amino, imino, amido, ureido, thioureido, ester, thioester, alkene, alkyne or alkyl; Y 1 -, Y 2 -, Y 3 -, Y 4 - and Y 5 - each independently represent a covalent link with the material's surface, or Y 1 -, Y 2 -, Y 3 -, Y 4 - and Y 5 - are each independently selected from the group consisting of OH, hydrogen, NO 2 , halogen, N 2 + A - , C 1-30 alkyl, carboxylic acid and derivatives thereof, acyl, -N 3 alkenyl or alkynyl. <EOS>