And presumably:
2.  Leonard Melchior STRAUB, b. aft. 1732

Comment:  A "pink" is a kind of ship, so did they come on the pink, Plaisance?  Or did they come on the ship, Pink Plaisance?  I suspect the former.

1a.  Israel Daniel Rupp.  1876.  A Collection of upwards of Thirty Thousand Names of German, Swiss, Dutch, French, and Other Immigrants in Pennsylvania from 1727 to 1776... Leary, Stuart, & Co., Philadelphia, PA (reprinted 1965/75 by Genealogical Publ. Co., Baltimore, MD; Broderbund CD-267).

p. 77	Sept. 21, 1732.  Palatines imported in the ship Pink Plaisance, John Paret, Master, from Rotterdam, last from Cowes.--Col. Rec. III. 459...
p. 78	Joh. Wilhelm Straub... Under sixteen... Joh. Bernhart Straub...

I've taken these to be father and son, but they may not be.  On the same ship:  Ulrich STEHLE. 

1b.  William Henry Egle, ed.  1890.  Names of Foreigners Who Took the Oath of Allegiance to the Province and State of Pennsylvania, 1727-1775, with the Foreign Arrivals, 1786-1808.  Pennsylvania Archives, 2nd ser., v. XVII, Harrisburg, PA (reprinted 1967/76 by Genealogical Publ. Co., Baltimore, MD; Broderbund CD-512):

p. 52	LIST OF FOREIGNERS IMPORTED IN THE SHIP PINK PLAISANCE, JOHN PARET, MASTER, FROM ROTTERDAM. QUALIFIED SEPT. 21, 1732.
p. 53	Joh. Wilhelm Straup... [The original list is herewith given.]...
p. 54	John Wm Stope [age] 44...
p. 57	Children... John Barnats Strop...

1c.  Ralph Beaver Strassburger.  1934.  Pennsylvania German Pioneers: a Publication of the Original Lists of Arrivals in the Port of Philadelphia, from 1727 to 1808.  Pennsylvania German Society, Norristown, PA (reprinted 1966/92 Genealogical Publ Co., Baltimore, MD; Broderbund CD-267).

p. 81	[List 22 B]  Palatines imported in the Pink Plaisance, John Parrett, Mr, from Rotterdam, but last from Cowes, p. Clearance thence.  Qualified Septr. 21st 1732...
p. 82	Johann Wilhelm Straub*...
p. 83	Johann Wilhelm Straub...

*The asterisk indicates his name was entered by a clerk (i.e., it is not his signature, which presumably means he was illiterate). 

2.  Frank F. Bell.  1960.  BELL-SHARPE.  MS, Dallas, TX (online at HeritageQuest at Genealogy.com):  Excerpt containing mention of our subject, most pertinently: 

p. 151

Letters of Administration on the estate of William Stroop, dec'd., were granted, 4 January (?), 1756, to Bernard Stroop, his son, and Leonard Mel Chor, a son of the widow of the deceased, the widow having renounced. (Ref:  Phila. Administration Book G., p. 42.)

The author had uniformly changed the varied spellings all to STROOP, so we don't know how the surname was spelled in the document, but probably not STROOP.  I don't understand the phraseology.  Wouldn't a son of the widow be a son of the testator? 

3.  The Palatine Project: 1732 Plaisance (online at the ProGenealogists web site).

[List 22 A, B, C] Plaisance (Pink) Captain: John Parrett From: Rotterdam By Way of: Cowes Arrival: Phildelphia, 21 Sep 1732
Name, Age	Place of Origin	Source	Remarks (spelling variations, etc.)
Johann Wilhelm Straub, 44 John Barnats Strop			Stope *For this Reformed schoolmaster and preacher, see Life of John Philip Boehm, p. 54.

The Souce here, though not given, was obviously Strassburger, but the important addition is the Remark.

4.  On 1 Apr 2006, a Google search turned up a GEDCOM posted to www.genealogyforum.com that mentions:  In August, 1743, John William STRAUB, paster of the Schmalzgass Reformed Congregation, did a baptism in Macungie Twp., Northampton [then Bucks, now Lehigh] Co., PA.

5.  Messages posted to the STRAUB Surname Board (online at Ancestry.com/RootsWeb.com), one of which includes mention of the next source.

6.

7.  Global Gazetteer (by Falling Rain Genomics, Inc.):  There are eight Gronau's in Germany, one of which is in Land Rheinland-Pfalz [the state of Rhineland-Palatinate].  Nearest major city is Mannheim (about 10 miles to the west, across the Rhine River in Baden-Württemberg).  Other sites turned up on a Google search shows Gronau is in Kreis Ludwigshafen.