NOVELTY - Preparing covalent organic frameworks (COFs) comprising a set of amine subunit, and a set of aldehyde subunits, involves: (a) adding a set of amine subunits to a first organic solvent; (b) adding a set of aldehyde subunits to a second organic solvent; and (c) mixing together the solutions obtained in steps (a) and (b).    USE - The method is useful for preparing covalent organic frameworks (COFs) used for coating surfaces, ink-jet printing and spray deposition, and for material encapsulation and coordination chemistry (all claimed).    ADVANTAGE - The method provides a suitable route for the synthesis of two-dimensional polyimine-based COFs from easily available starting materials under soft conditions with high degree of processability and structures with localization, order and sizes predetermined on demand.    DETAILED DESCRIPTION - Preparing covalent organic frameworks (COFs) comprising a set of amine subunits selected from diamines of Formula (I), triamines of Formula (Ia) and tetraamines of Formula (Ib), and a set of aldehyde subunits selected from dialdehydes of Formula (II), trialdehydes of Formula (IIa) and tetraaldehydes of Formula (IIb); and where: (i) each diamine subunit of Formula (I) is bonded with at least one aldehyde subunit of Formula (IIa) or (IIb), by an imine bond, (ii) each triamine of Formula (Ia) is bonded to at least one aldehyde subunit of Formula (II) or (IIa), by an imine bond, or (iii) each tetramine of Formula (Ib) is bonded to at least one aldehyde subunit of Formula (II) or (IIb), by an imine bond; where the method involves: (a) adding a set of amine subunits of Formula (I), (Ia) or (Ib) to a first organic solvent; (b) adding a set of aldehyde subunits of Formula (II), (IIa) or (IIb) to a second organic solvent; and (c) mixing together the solutions obtained in steps (a) and (b).R1=substituted and un-substituted aryl groups, and substituted and un-substituted macrocyclic groups.    R2=substituted and un-substituted aryl groups, and substituted and un-substituted macrocyclic groups.    INDEPENDENT CLAIMS are included for:    (1) COFs obtainable according to the method; and    (2) a device selected from solar cells, flexible displays, lighting devices, sensors, photoreceptors, batteries, capacitators, gas storage devices and gas separation devices, which comprises the COFs.