computer mrie~.80 ChemPlate and Hopkins, a Template and Font for Drawing Molecular Structures with the Macintosh Computer Jih Ru Hwu', John M. Wetzel, and Jeflrey A. Robl
The Johns Hopkins University Baltimore. MD 21218 Chemists should be skilled in drawing molecular structures in order to communicate effectively with others in their field. Undergraduate students begin to learn about the shapes and stereoconfigurations of organic molecules in general chemistry and introductory organic chemistry courses. However, there is often too little class time available for teachine students how to draw oreanic structures in such courses. Thesame isgenerally true for advanced classes. As a result, many chemistrv maiors complete their underaraduate tr&ingwithout acquiring the skills needed to represent molecular structures correctly on paper. This problem is frequently evident in organic chemistry papers submitted by undergraduate and graduate students. A deficiency is also apparent when students are reluctant to use chalkboards to communicate with audiences during chemistry seminars. Their reluctance may result in part from a lack of skill in copying the images of molecules from their minds to the chalkboard. We feel that there is a need for some means to develop the drawing skills of undergraduate and graduate students without usina class time that would otherwise be spent on other aspectsof chemistry. Many students now have access to personal computers with graphics capabilities. I t is becoming common for students to use computers to complete assignments for their coursework. Improving students' chemical drawing skills would be another valuable application of computers. We wish to report on a method by which students can develop their drawing skills using the Apple Macintosh personal computer while thev comolete assienments for chemistrv classes. ~rofessionaichekists mayalso find this metho; useful for preoarina chemical structure diaarams for puhlications and slide presentations. Chemists tvpicallv prepare molecular structures bv means of ~ a p i d o g r a p perk h a n d chemical templates or commercial dry-transfer symbols. Both of these methods are time consuming and tedious. Personal computers now have the capability to make this task much easier, provided that one has the right software. Apple's MacDraw program for the Macintosh has the canabilitv to oroduce chemical structure diaarams.2 Good bualit; hardcopies of these diagrams can be ohained with a suitable printer. T o enhance the utility and convenience of MacDraw, we have prepared our own chemical template computer document, which we call ChemPlate. I t contains the basic structural units that we normally use in drawing organic molecules. These basic units can he transferred easi-
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Research Fellow of the Alfred P. Sloan Foundation. 1986-1988. and author to whom correspondence should be addressed. For a review of MacDraw discussing its usefulness for drawing chemical structures, see Whitesell, J. K. J. Am. Chern. Soc. 1985, 107.6140.
edited by JOHN W. MOORE
Eastern Michigan university, Ypsiimti,
48197
ly from ChemPlate to a working document for assembly to form molecules, equations and schemes. We have also prepared a font, called Hopkins, for adding letters, numbers and symbols to our diagrams. It has a variety of special features that make it ideal for use with a chemical drawing oromam. We helieve that use of our temolate and font with ~ a i ~ r will a walso benefit chemistry st&ents by helping to develon their drawine" skills while thev comolete term papers, laboratory reports, and problem sets for chemistry classes. Features of ChemPlate and Hopkins
ChemPlate (version 1.2) occupies 37K of disk space and can be used in conjunction with MacDraw on a 512K Macintosh and Macintosh Plus. It contains over 200 objects (see Fig. 11,including two-dimensional, three-dimensional, edgewise, and perspective representations of various hydrocarbon rings and ring systems; rings with empty spaces left for -~ the inclusion of heteroatoms; perspective representations of a tetrasubstituted C=C double bond and a tetrahedral carbon center; Newman projection skeletons; large brackets; nine sets of bonds oriented in various directions, including short bonds for use with tvoed ". characters: arrowheads for drawing curved-arrow mechanisms and equations; and various small svmbols. These basic structural units were drawn acrording to a single scale, so that they ran Iw joined easily to iorm complex structures. This scale is hased on a lenrtb of 2.2 cm f&a carbon-carbon bond in a flat cyclohexane&g. Hopkins is a 36-point font that occupies 18K of disk space. It is similar in style to the Geneva font that is included with the MacDraw program, but it possesses several advantages for making chemical diagrams: ~
(11 L ' p p ~ rand lower C&P letters are the proper sircc t o match structures n~nden i t h Chctnl'lnte. Nutr that vcrv fpw Rd-point font, *r i t h shnrply detined chnraotera are currrntly svailahle t'or
Maeintoshes not equipped with a laser printer. (2) Use of the "Bold" style option with Hopkins makes the thickness of the lines in mast characters (e.g.,"H")the same as the thickness of asingle bond in a typical ChemPlatestructure. The same lines in other fonts are considerably narrower, even with theBold option. Hopkinscan also be used with the"P1ainText" option, if desired. (3) Super- and subscript Arabic numerals of the proper size to accompany letters can he typed directly from the keyboard. This is a very convenient feature because there is no command available in MacDraw for making super- or subscript characters. (4) Commonly used Greek letters, such as n,8, u, 6, c, 8, A, p, v, r,2, r , and w , have been included. ( 5 ) Arrows painting left and right can be typed and the lines can he extended. These arrows can be used directly in chemical equations. (6) The font includeseommonly used symbols, such as and A.
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Using ChemPlate
T o create a diagram, the ChemPlate document is opened in the normal fashion. The user then selects objects, such a s rings and bonds, from ChemPlate by pointing to each one with the mouse and clicking the mouse button. Several ohjects can he selected a t once by holding down the Shift key on the keyboard and "clicking" on each object with the mouse. T h e selected objects are transferred to a new document, where they can be assembled and grouped to form more complex structures. Volume 64
Number 2
February 1987
135
Figure 1. The contents of ChemPlate (version 1.2). When printed normal size, the cyclohenane ring in the upper lelt corner has a C-C line thickness of approximately 2 mm.
bond length of 2.2 crn and a
Hopkins characters can he added to a structure or equation either by clicking with the typing tool directly a t the desired location and typing, or by clicking elsewhere, typing, and dragging the characters to the desired location with the mouse. The latter method allows more orecise nositionine of the characters. Several of the tools and commands in MacDraw have special applications that are particularly useful for preparing chemical structure diagrams:
ChemPlate contains the basic units most commonly required to build organic structures efficiently. Users have the option of preparing additional template structures, either by combining the units in ChemPlate or by using the tools of MacDraw to make new ones. However. addine more structures to ChemPlate may impede the'drawing process by increasine the time reouired to ooen or activate the ChemPlate document.
Holdine down the Ootion kev while draeeine charac. . .. Hookins . tcr;uith thr i n l u s r n,.~krrfh~ardcreri (and nur just a ractan; : h r h d r r , \.iiihle. alldwm: thmm t u be p
