File Name : figures1.tif Caption : figure s1. 2d histograms of the four groups of g-z traces differentiated by the clustering-based analysis of (a)-(d) 7-hbc-sme and (e)-(h) hbc-sme g-z traces. the percentages indicated in the panels refer to the percentage of g-z traces used in each 2d histogram respect to the total number of recorded g-z traces that display plateaus. no significant differences are observed either in the shape of the histogram or the probability of each group for the two compounds. File Name : figures2.tif Caption : figure s2. a) 1d histograms built for the different groups of g-z traces obtained from the clustering-based analysis for hbc-sme and 7-hbc-sme, and b) their corresponding plateau-length distributions. File Name : figures3.tif Caption : figure s3. individual g-z traces for 7-hbc-sme, corresponding to the four groups previously described. black: broken plateaus; red: long plateaus; cyan: short plateaus: pink: inclined plateaus. File Name : figures4.tif Caption : figure s4. results for the single-molecule experiments for 7-hpb-sme. a) 2d histogram of all traces displaying plateaus; b) plateau-length distribution in comparison with that of 7-hbc-sme. File Name : figures5.tif Caption : figure s5. 1d histograms obtained for 7-hbc-alk in 4 different experimental runs. the value indicated for each run corresponds to the percentage of traces with plateaus respect to the total number of recorded traces. the main features are reproduced in all histograms, although with different weight, reflecting different occurrence of the different possible configurations. File Name : figures6.tif Caption : figure s6. individual g-z traces for 7-hbc-alk. four examples are shown for traces in groups a (black), b (red) and c (green) separated using a clustering-based analysis. File Name : figures7.jpg Caption : figure s7. plateau-length distributions for groups a, b and c and d found for 7-hbc-alk (a-c) and hbc-alk (d-f), showing separately the length at the end of the flat region and at the end of the final cloud for the groups a and b of each molecule. the length values marked as vertical lines correspond to the expected junction length for each molecule, considering the distance from the middle of the au-c bond. File Name : figures8.tif Caption : figure s8. 2d histograms of log(g/g0) vs v (a and c) and log(i/a) vs v (b and d) built from the -1.5 -1.5 voltage ramps along the molecular plateaus for 7-hbc-sme and hbc-sme. File Name : figures9.tif Caption : figure s9. 2d histograms of log(g/g0) vs v (a and b) and log(i/a) vs v built from the -1.5 - +1.5 (b and e) and -0.5 – +0.5 (c and f) voltage ramps along the molecular plateaus for 7-hbc-alk and hbc-alk. File Name : figures10.pdf Caption : figure s10. visual representation of the homo for hbc-sme, 7-hbc-sme, hbc-alk and 7-hbc-alk File Name : figures11.pdf Caption : figure s11. local density of states (ldos) projected on the molecule for 7-hbc-sme, hbc-sme, 7-hbc-alk and hbc-alk in the top binding position. File Name : figures12.pdf Caption : figure s12. total transmission (ttot) and transmission of the most dominant channel (t1) for 7-hbc-sme, hbc-sme, 7-hbc-alk and hbc-alk in the top binding position. the dashed-point curves are relative to lower-contribution channels. File Name : figures13.pdf Caption : figure s13. transmission curves obtained by the tb approach for the 7-hbc and hbc compounds ending with sme (top) and alkyne (bottom) groups. File Name : figures14.pdf Caption : figure s14. assignment of the atom indexes corresponding to the coupling values listed in table s2 File Name : figures15.pdf Caption : figure s15. molecular junctions comprising 7-hpb-sme (a), terphen-sme (b) and ope3-sme (c), and corresponding transmission curves (d), compared with those of 7-hbc-sme and hbc-sme already shown in the main text. File Name : figures17.pdf Caption : figure s17: electron density for 7-hbc-alk and ch2 7-hbc-alk. the co group in 7-hbc-alk is electron-withdrawing, attracting charge density, whereas the ch2 is donating, thus surrounded by less charge density than the rest of the molecules. File Name : figures16.pdf Caption : figure s16: transmission curves (a) for hbc-alk (cyano) and 7-hbc-alk (blue) in the top (solid line) and bridge (dashed line). 7-hbc-alk (b) and hbc-alk (c) in the bridge binding positions corresponding to the curves shown in panel a. File Name : figure s18.tif Caption : figure s18. electrochemical experiments using a solution of 0.1 m kcl as electrolyte in milli-q water with 0.01 m of [fe(cn)6] 3−/4− as redox marker. bare au and functionalized substrates were used as working electrode, a pt wire as counter electrode and an ag/agcl electrode as reference. cv recorded at 0.1 v·s-1 scan rate. File Name : figures19.tif Caption : figure s19. jv characteristics (heat map plots) of the egain/gaox/sams/auts for a) hbc-alk, b) 7-hbc-alk, c) hbc-sme and d) 7-hbc-sme sams.